U.S. patent application number 10/766621 was filed with the patent office on 2004-09-30 for apparatus for selectively connecting a telephone to a telephone network or the internet and methods of use.
This patent application is currently assigned to ACTIONTEC ELECTRONICS, INC.. Invention is credited to Chang, Tsung-Yen Dean, Gu, Bin Lang, Ho, Chee Hin, Li, Chuang.
Application Number | 20040192292 10/766621 |
Document ID | / |
Family ID | 24058759 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040192292 |
Kind Code |
A1 |
Chang, Tsung-Yen Dean ; et
al. |
September 30, 2004 |
Apparatus for selectively connecting a telephone to a telephone
network or the internet and methods of use
Abstract
Apparatus and methods are provided for selectively providing
telephone service that is either PSTN-based on Internet-based using
a standard analog telephone circuit. In a first embodiment, the
apparatus comprises a hardware module and associated software for
coupling a personal computer or Internet appliance and a standard
analog telephone. The apparatus includes a DTMF interface circuit,
a subscriber line interface circuit, a ring detection circuit, and
an interface circuit for interfacing with the PC or Internet
appliance. The apparatus permits the analog telephone to be toggled
between an Internet-based telephone mode and a PSTN-network mode by
inputting a predetermined sequence of DTMF digits. In alternative
embodiments, the apparatus comprises a processor, modem and
optionally, analog telephone circuit, to provide a stand-alone or
partially-integrated device capable of selectively switching
between PSTN-based and Internet-based telephony services.
Inventors: |
Chang, Tsung-Yen Dean; (Los
Altos Hills, CA) ; Li, Chuang; (Saratoga, CA)
; Ho, Chee Hin; (San Jose, CA) ; Gu, Bin Lang;
(Sunnyvale, CA) |
Correspondence
Address: |
FISH & NEAVE
1251 AVENUE OF THE AMERICAS
50TH FLOOR
NEW YORK
NY
10020-1105
US
|
Assignee: |
ACTIONTEC ELECTRONICS, INC.
Sunnyvale
CA
94086
|
Family ID: |
24058759 |
Appl. No.: |
10/766621 |
Filed: |
January 27, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10766621 |
Jan 27, 2004 |
|
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09517194 |
Mar 2, 2000 |
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6700956 |
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Current U.S.
Class: |
455/426.1 ;
455/417; 455/445 |
Current CPC
Class: |
H04M 1/2473 20130101;
H04M 1/2535 20130101 |
Class at
Publication: |
455/426.1 ;
455/417; 455/445 |
International
Class: |
H04Q 007/20; H04M
003/42 |
Claims
What is claimed is:
1. Apparatus for selectively coupling an analog telephone circuit
to either a telephone network or an Internet telephony service, the
apparatus comprising: an interface adapted to be coupled to a PC; a
jack adapted to be coupled to the telephone network to pass analog
signals to the telephone network; a DTMF interface circuit adapted
to be coupled to the analog telephone circuit; and a switch coupled
to the telephone, the switch having a first position wherein the
telephone is coupled to the jack and a second position wherein the
telephone is coupled to the interface, the switch moving between
the first and second positions responsive to detection of a
predetermined sequence of DTMF digits through the DTMF interface
circuit.
2. The apparatus of claim 1 wherein the DTMF interface circuit
further comprises a DTMF detection circuit.
3. The apparatus of claim 1 further comprising a subscriber line
interface circuit, the subscriber line interface circuit coupled
between the switch and the interface when the switch is in the
second position.
4. The apparatus of claim 1 further comprising a hold circuit
coupled between the jack and the interface.
5. The apparatus of claim 1 further comprising a ring detection
circuit coupled between the jack and the interface.
6. The apparatus of claim 1 further comprising an off-hook
detection circuit coupled between the telephone and the
interface.
7. The apparatus of claim 1 further comprising a modem detection
circuit coupled between the jack and the interface.
8. The apparatus of claim 1 further comprising a call-waiting
detection circuit coupled between the jack and the interface.
9. The apparatus of claim 1 further comprising a line detection
circuit coupled between the jack and the interface.
10. The apparatus of claim 1 wherein the interface further
comprises a microcontroller.
11. The apparatus of claim 1 further comprising circuitry for
digitizing voice signals coupled to the interface.
12. The apparatus of claim 1 wherein the predetermined sequence of
DTMF digits comprises one of the sequences selected from the group
consisting of "##", "* *", "*#" and "#*".
13. The apparatus of claim 1 wherein the interface is adapted to be
coupled to an expansion slot of a PC.
14. The apparatus of claim 13 wherein the interface has a PCI or
ISA form factor.
15. The apparatus of claim 14 wherein the interface comprises a
portion of a modem circuit or sound card.
16. The apparatus of claim 1 wherein the interface is a serial
port, a parallel port, or a Universal Serial Bus port.
17. The apparatus of claim 16 wherein the interface comprises a
portion of a modem circuit.
18. A method of selectively coupling an analog telephone circuit to
either a telephone network or an Internet telephony service, the
method comprising: providing apparatus adapted to be coupled to a
PC, an analog telephone circuit, and a telephone network, the
apparatus including an interface, a DTMF interface circuit and a
switch coupled to the telephone and the DTMF interface circuit, the
switch having a first position wherein the telephone is coupled to
the telephone network and a second position wherein the telephone
is coupled to the interface, the switch responsive to detection of
a predetermined sequence of DTMF digits by the DTMF interface
circuit; coupling the apparatus to a PC, an analog telephone
circuit, and the telephone network; and if it is desired to connect
to the telephone network, dialing a telephone number while the
switch is in the first position; if it is desired to place an
Internet-based telephone call, entering the predetermined sequence
of DTMF digits to cause the switch to move to the second
position.
19. The method of claim 18 further comprising, after entering the
predetermined sequence of DTMF digits, launching an Internet-based
telephony application on the PC.
20. The method of claim 18 further comprising establishing an
Internet-based telephone call.
21. The method of claim 18 further comprising, during the pendency
of an Internet-based telephone call: receiving a call-waiting
signal that there is an incoming call on the first telephone
network line; and generating a user-perceptible signal responsive
to receipt of the call-waiting signal.
22. The method of claim 21 further comprising: entering the
predetermined sequence of DTMF digits to cause the switch to move
from the second to the first position; and accepting the incoming
call.
23. The method of claim 18 wherein the apparatus further comprises
a ring detection circuit, the method further comprising during the
pendency of an Internet-based telephone call: receiving an incoming
call on the telephone network; detecting the incoming call on the
telephone network using the ring detection circuit; and generating
a user-perceptible signal responsive to an output of the ring
detection circuit.
24. The method of claim 23 further comprising: entering the
predetermined sequence of DTMF digits to cause the switch to move
from the second to the first position; and accepting the incoming
call on the telephone network.
25. The method of claim 24 further comprising, during the pendency
of the call on the telephone network: entering the predetermined
sequence of DTMF digits to cause the switch to move from the first
to the second position; and resuming the Internet-based telephone
call.
26. A telephone comprising: a jack adapted to be coupled to a
telephone network; an analog telephone circuit; a microprocessor; a
modem coupled to the microprocessor; and a switching circuit having
a first position wherein the analog telephone circuit is coupled to
the jack for transmitting and receiving analog voice signals over
the telephone network, and a second position wherein the analog
telephone circuit is coupled to the jack through the microprocessor
and modem for transmitting digitized voice signals over the
Internet.
27. The telephone of claim 26 further comprising a digital signal
processor.
28. The telephone of claim 26 further comprising a coding/decoding
circuit.
29. The telephone of claim 26 further comprising a subscriber line
interface circuit coupled between the analog telephone circuit and
the microprocessor.
30. The telephone of claim 26 further comprising circuitry for
detecting a call waiting signal.
31. The telephone of claim 26 further comprising circuitry for
detecting a ring signal.
32. The telephone of claim 26 further comprising a button, and the
switching circuit moves between the first and second positions
responsive to actuation of the button.
33. A method of selectively coupling an analog telephone circuit to
either a telephone network or an Internet telephony service, the
method comprising: providing apparatus adapted to be coupled to a
telephone line, the apparatus including a jack, an analog telephone
circuit, a microprocessor, a modem, and a switching circuit, the
switching circuit having a first position wherein the analog
telephone circuit is coupled to the jack for transmitting and
receiving analog voice signals over the telephone network, and a
second position wherein the analog telephone circuit is coupled to
the jack through the microprocessor and modem for transmitting
digitized voice signals over the Internet; coupling the jack to the
telephone line; and if it is desired to connect to the telephone
network, dialing a telephone number while the switching circuit is
in the first position; if it is desired to place an Internet-based
telephone call, actuating the switching circuit to cause the
switching circuit to move to the second position.
34. The method of claim 33 further comprising, after moving the
switching circuit to the second position, executing an
Internet-based telephony application by the microprocessor.
35. The method of claim 33 further comprising establishing an
Internet-based telephone call.
36. The method of claim 33 further comprising, during the pendency
of an Internet-based telephone call: receiving a call-waiting
signal that there is an incoming call; and generating a
user-perceptible signal responsive to receipt of the call-waiting
signal.
37. The method of claim 36, wherein the telephone further comprises
a button coupled to the switching circuit, the method further
comprising: actuating the button to cause the switching circuit to
move from the second to the first position; and accepting the
incoming call.
38. The method of claim 37 further comprising, after accepting the
incoming call, actuating the button again to return to the
Internet-based telephone call.
39. The method of claim 33 further comprising, during the pendency
of an Internet-based telephone call: receiving a ring signal that
there is an incoming call; and generating a user-perceptible signal
responsive to receipt of the ring signal.
40. The method of claim 39, wherein the telephone further comprises
a button coupled to the switching circuit, the method further
comprising: actuating the button to cause the switching circuit to
move from the second to the first position; and accepting the
incoming call.
41. The method of claim 40 further comprising, after accepting the
incoming call, actuating the button again to return to the
Internet-based telephone call.
42. A module for selectively using a telephone to place calls via
the Internet or PSTN network, the module comprising: a first jack
adapted to be coupled to an analog telephone; a second jack adapted
to be coupled to a telephone network; a microprocessor; a modem
coupled to the microprocessor; and a switching circuit having a
first position wherein first jack is coupled to the second jack for
transmitting and receiving analog voice signals from an analog
telephone over the telephone network, and a second position wherein
the first jack is coupled to the second jack through the
microprocessor and modem for transmitting digitized voice signals
over the Internet.
43. The module of claim 42 further comprising a digital signal
processor.
44. The module of claim 42 further comprising a coding/decoding
circuit.
45. The module of claim 42 further comprising a subscriber line
interface circuit coupled between the first jack and the
microprocessor.
46. The module of claim 42 wherein the modem further comprises
circuitry for detecting a call waiting signal.
47. The module of claim 42 wherein the modem further circuitry for
detecting a ring signal.
48. The module of claim 42 further comprising a button, and the
switching circuit moves between the first and second positions
responsive to actuation of the button.
49. A method of selectively coupling an analog telephone to either
a telephone network or an Internet telephony service, the method
comprising: providing apparatus adapted to be coupled to an analog
telephone via a first jack and a telephone line via a second jack,
a microprocessor, a modem, and a switching circuit, the switching
circuit having a first position wherein the first jack is coupled
to the second jack for transmitting and receiving analog voice
signals from an analog telephone over the telephone network, and a
second position wherein the first jack is coupled to the second
jack through the microprocessor and modem for transmitting
digitized voice signals over the Internet; coupling the first jack
to a telephone; coupling the second jack to a telephone line; and
if it is desired to place a telephone call using the telephone
network, dialing a telephone number while the switching circuit is
in the first position; and if it is desired to place an
Internet-based telephone call, actuating the switching circuit to
cause the switching circuit to move to the second position.
50. The method of claim 49 further comprising, after moving the
switching circuit to the second position, executing an
Internet-based telephony application by the microprocessor.
51. The method of claim 49 further comprising establishing an
Internet-based telephone call.
52. The method of claim 49 further comprising, during the pendency
of an Internet-based telephone call: receiving a call-waiting
signal that there is an incoming call; and generating a
user-perceptible signal responsive to receipt of the call-waiting
signal.
53. The method of claim 52, wherein the telephone further comprises
a button coupled to the switching circuit, the method further
comprising: actuating the button to cause the switching circuit to
move from the second to the first position; and accepting the
incoming call.
54. The method of claim 52 further comprising, after accepting the
incoming call, actuating the button again to return to the
Internet-based telephone call.
55. The method of claim 49 further comprising, during the pendency
of an Internet-based telephone call: receiving a ring signal that
there is an incoming call; and generating a user-perceptible signal
responsive to receipt of the ring signal.
56. The method of claim 55, wherein the telephone further comprises
a button coupled to the switching circuit, the method further
comprising: actuating the button to cause the switching circuit to
move from the second to the first position; and accepting the
incoming call.
57. The method of claim 56 further comprising, after accepting the
incoming call, actuating the button again to return to the
Internet-based telephone call.
Description
BACKGROUND OF THE INVENTION
[0001] Internet telephony services are known that permit an
Internet user with a personal computer equipped with a sound card,
speaker, microphone and modem to initiate a call from the computer
and transmit the call over the Internet to a telephone connected to
the public switched telephone network ("PSTN") or to another
similarly equipped personal computer. For example, Net2phone, Inc.,
Dialpad, Inc., and MediaRing, Inc. provide software and services
that permit an Internet user to place a call from their computer,
and communicate with the called party using the sound card, speaker
and microphone of the caller's computer.
[0002] Internal computer cards, such as the Internet PhoneJACK.TM.,
available from Quicknet Technologies, Inc., San Francisco, Calif.,
permit a user of the foregoing services to connect a standard
analog telephone to the personal computer, for use in placing and
receiving Internet telephone calls. A telephone coupled to such an
internal computer card, however, cannot be switched to place a
telephone call using the PSTN unless it is physically unplugged
from the internal computer card and then reconnected to the
telephone network.
[0003] Net2phone, Inc., also provides a service called "Net2phone
Direct" that permits users to use a standard analog telephone to
place a call over the Net2phones Internet Telephony network. In
this system, the user dials a local number to access Net2phone,
Inc.'s gateway, which then prompts the user for an account number
and the telephone number of the party to be called. The system
digitizes the user's voice and transmits the call over the Internet
to another gateway located near the called party. That gateway
switches the call to the local PSTN network to complete the call.
Although the user does not need an Internet account to place a call
using this system, the user must have an account with Net2phone,
Inc., and is limited to using the telephone with that service.
Further, the user may not switch between an Internet call and a
PSTN call without terminating the Internet call.
[0004] Net2phone, Inc., also has announced an agreement to develop
a specialized telephone that can be used to select between
PSTN-based long distance telephone service and Internet-based long
distance service by pressing a button on the telephone. The user
must register the telephone and must select a flat fee arrangement
for the Internet-based long distance service. The proposed
telephone must be purchased, and may not be usable with other
Internet-based telephony services. In addition, it is unclear
whether a user can switch between a PSTN-based call and an Internet
call without terminating the other call. For example, if a user
were engaged in an Internet-based telephone call and received an
incoming call from the PSTN network, it is unclear whether the user
could receive a call-waiting notification, and if so, whether the
user could accept the incoming call without first terminating the
Internet-based call.
[0005] It would therefore desirable to provide apparatus and
methods that permit a user to seamlessly and dynamically switch
between Internet-based telephony service and PSTN-based telephony
service.
[0006] It further would be desirable to provide apparatus and
methods that enable a standard analog telephone circuit to be
selectively connected to either the PSTN network or an
Internet-based telephony service.
[0007] It also would be desirable to provide apparatus and methods
that detect the presence of PSTN network service and provides
either the PSTN network dial tone or a synthesized dial tone when
handset is taken off-hook.
[0008] It still further would be desirable to provide apparatus and
methods, useable in conjunction with call-waiting capable modems,
that enable a user to receive a call-waiting signal and switch
between Internet-based telephony service and PSTN-based telephony
service.
[0009] It also would be desirable to provide apparatus and methods
that enable a user to receive a ring signal and switch between
Internet-based telephony service and PSTN-based telephony
service.
[0010] It yet further would be desirable to provide apparatus and
methods that enable a user to seamlessly switch between
Internet-based and PSTN-based telephony service using a device that
incorporates a microprocessor and modem, and optionally, an analog
telephone circuit.
SUMMARY OF THE INVENTION
[0011] In view of the foregoing, it is an object of this invention
to provide apparatus and methods that permit a user to seamlessly
and dynamically switch between Internet-based telephony service and
PSTN-based telephony service.
[0012] It is also an object of the present invention to provide
apparatus and methods that enable a standard analog telephone
circuit to be selectively connected to either the PSTN network or
an Internet-based telephony service.
[0013] It is a further object of this invention to provide
apparatus and methods that detect the presence of PSTN network
service and provides either the PSTN network dial tone or a
synthesized dial tone when handset is taken off-hook.
[0014] It is another object of this invention to provide apparatus
and methods, useable in conjunction with call-waiting capable
modems, that enable a user to receive a call-waiting signal and
switch between Internet-based telephony service and PSTN-based
telephony service.
[0015] It is also an object of the present invention to provide
apparatus and methods that enable a user to receive a ring signal
and switch between Internet-based telephony service and PSTN-based
telephony service.
[0016] It is yet another object of the present invention to provide
apparatus and methods that enable a user to seamlessly switch
between Internet-based and PSTN-based telephony service using a
device that incorporates a microprocessor and modem, and
optionally, an analog telephone circuit.
[0017] These and other objects of the present invention are
accomplished by providing a hardware or software switch adapted to
selectively couple a standard analog telephone circuit to either a
suitably equipped personal computer (or other computing machine
capable of accessing the Internet, such as Internet appliances) or
the PSTN network. By activating a feature of the device, e.g.,
using a predetermined sequence of DTMF digits or by pressing a
button, the switch permits the analog telephone circuit to be used
with either an Internet-based telephony service or PSTN-based
telephone service.
[0018] In a first embodiment, the switch comprises an external
computer peripheral module that may be coupled to standard analog
telephone circuit (e.g., a standard analog telephone) and to the
computing device using a parallel or serial port, or connection to
a Universal Serial Bus (USB). Alternatively, the computer
peripheral module may take the form of an internal computer card
that is connected a standard analog telephone circuit and to the
system bus of the computing device using, for example, a PCI or ISA
expansion card slot. In this embodiment, the module preferably
includes at least a DTMF interface circuit, a subscriber line
interface circuit and a switch movable between a first position,
wherein the analog telephone circuit is coupled to the PSTN
network, and a second position, where the analog telephone circuit
is coupled to the computing device.
[0019] In a second embodiment, a specialized telephone is provided
that combines the switch of the first embodiment with key
components of the computing device, such as the modem and
microprocessor, and the analog telephone circuit. In this
embodiment, the specialized telephone includes a button that may be
used by the caller to toggle between Internet-based and PSTN-based
telephony services, without dropping the other call.
[0020] In yet a third embodiment, an alternative specialized module
is provided, suitable for connection to a standard analog
telephone, that incorporates the switch of the first embodiment and
the basic components of a computing device needed to establish and
maintain an Internet connection, such as a microprocessor,
associated hardware, and modem.
[0021] In accordance with the methods of the present invention, the
apparatus is programmed with software routines to control operation
of the switch. The software preferably includes user-selectable
settings including, for example, the default mode of operation
(either PSTN network or Internet service), the telephone number for
dialing into the Internet based service and appropriate
log-in/password information. The software also includes routines
for switching between modes of telephony service, as well the
capability to handle call-waiting and second-line operation of the
telephone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Additional objects and advantages of the invention will be
apparent from the following description, the accompanying drawings
and the appended claims, in which:
[0023] FIG. 1 is a schematic view showing use of the apparatus of
the present invention to selectively place and receive calls from
either the Internet or the PSTN network;
[0024] FIG. 2 is a schematic view of the internal components of a
first embodiment of the apparatus of the present invention;
[0025] FIG. 3 is a schematic view of the internal components of a
preferred implementation of the first embodiment of the apparatus
of the present invention;
[0026] FIG. 4 is a schematic view of the internal components of an
alternative embodiment of the apparatus of the present invention
having an expansion slot form factor;
[0027] FIG. 5 is a flow diagram depicting operation of the
apparatus of the present invention during placement of telephone
call;
[0028] FIG. 6 is a flow diagram depicting operation of the
apparatus of the present invention in response to detection of a
call waiting signal received from the PSTN network;
[0029] FIG. 7 is a flow diagram depicting operation of the
apparatus of the present invention where a second line to the PSTN
network is available;
[0030] FIGS. 8A-8C are schematic views showing connection of the
apparatus of the present invention to personal computers having
access to the Internet via DSL, cable and ISDN services,
respectively;
[0031] FIGS. 9A and 9B are, respectively, a perspective view and a
schematic diagram of a second embodiment of the apparatus of the
present invention in the form of a specialized telephone; and
[0032] FIGS. 10A and 10B are, respectively, a perspective view and
a schematic diagram of a third embodiment of the apparatus of the
present invention in the form of a specialized module that includes
the a microprocessor and modem.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The apparatus and methods of the present invention permit a
user to selectively place or receive a telephone call using either
the PSTN network or an Internet telephony service, using a standard
analog telephone circuit and a personal computer or Internet
appliance equipped with a sound card, microphone, speaker and
modem. As used herein, a "PC" refers not only to a previously known
personal computer having a sound card, speakers, and modem, but
also to any and all other computing devices capable of establishing
a connection to the Internet to transmit and receive VOIP data
transmissions, such as Internet appliances. Further, as used in
this written description, the term "analog telephone circuit" and
"analog telephone" are interchangeable and refer to previously
known analog telephone circuits such as are used in conventional
telephones, whether or not embodied in the form of a previously
known telephone receiver and handset.
[0034] In accordance with the present invention, the user may place
an out-going call with either the PSTN network or an Internet-based
telephony service, may receive an incoming call from either network
when already engaged in an outgoing call, and may toggle between
calls placed on either or both networks where a second PSTN line is
available. Advantageously, a first embodiment of the present
invention does not require that the user purchase a specialized,
limited-use telephone, as in previously known methods, and offers a
virtually unlimited choice of Internet telephony service providers.
Additional embodiments include specialized modules, either with or
without a standard analog telephone circuit, that permit the user
to establish telephone calls over either the Internet or PSTN
network without coupling the module to a separate computing
device.
[0035] In particular, the present invention provides a system,
including hardware and bundled software, that allows connection of
a standard analog phone to a PC and which permits the telephone to
be used selectively to place and receive either PSTN or
Internet-based telephone calls. In one embodiment, the apparatus
permits the use of a short series of keystrokes input using the
telephone dial pad, e.g., "##", "**", "*#" or "#*", to toggle
between the PSTN network and Internet telephony service. The
apparatus of the present invention may be implemented in any of
several form factors, including an external computer peripheral
adapted for connection to a PC via known parallel, serial or USB
ports, or an internal card adapted to engage an expansion slot on
the PC motherboard. Depending upon the implementation chosen, the
apparatus may include a microprocessor controller, or may rely upon
the central processing unit and/or modem of the PC to handle
certain of the call processing functions.
[0036] In an alternative embodiment, the present invention
surpasses previously known special-purpose telephones by offering
the capability to toggle between active calls on both the Internet
and PSTN services, and the capability to handle call-waiting
traffic.
[0037] Referring now to FIG. 1, a first embodiment of the apparatus
and methods of the present invention are described suitable for use
with previously known PCS to enable telephone calls to be placed
and received selectively using either the PSTN network or the
Internet. Apparatus 10 of the present invention is shown connected
to standard analog telephone set 11 having handset 12 and dial pad
13, and previously known PC 14 having monitor 15, keyboard 16 and
mouse 17. PC 14 includes an internal modem for dialing into
Internet 19 via PSTN network 18, as is well known. Telephone 20,
which includes a standard analog telephone circuit, is connected to
PSTN 18, and may in addition be connected to Internet 19 via an
Internet gateway and a previously known Internet telephony service
provider, such as that provided by Net2phone, Inc.
[0038] Apparatus 10 is coupled to a data port of PC 14 via data
cable 21. Where the user has a single telephone line from the PSTN
network, apparatus 10 is coupled to the telephone jack of the
internal modem of PC 14 via cable 22; where two separate PSTN lines
are available (e.g., two separate telephone numbers), a first line
may be coupled to the internal modem of PC 14, while the second
line may be coupled directly to apparatus 10 using cable 22, for
the purposes described hereinafter.
[0039] Apparatus 10 is coupled to telephone 11 via standard two
wire telephone cable 23. In accordance with the present invention,
apparatus 10 permits telephone 11 to be used to place or receive
calls over either PSTN 18 alone, or using PC 14, over Internet 19,
as described in detail hereinafter. As will of course be apparent,
apparatus 10 may be used to place/receive calls not only. over
Internet 19, but in addition may be used for placing calls over any
wide-area network supporting telephony using Voice Over Internet
Protocol ("VOIP").
[0040] Referring to FIG. 2, a schematic diagram depicting a
simplified internal structure for a first embodiment of apparatus
10 is described. FIG. 2 shows, to the right of dotted line A, the
basic components of the switch of the present invention, while the
components to the left of dotted line depict elements typically
expected to be used to implement the apparatus. As will be apparent
later in this written description, it may be desirable to include
other circuits to enhance usability of the invention.
[0041] Apparatus 10 includes jack 30 for accepting cable 22 coupled
to the telephone pass-through jack of the internal modem of PC 14
(where a single PSTN line is available) or directly to the PSTN
network (where two lines are available). Jack 31, e.g., a standard
RJ-11 jack, accepts cable 23 coupled to telephone 11; data port 32
accepts data cable 21 from PC 14. Jack 31 is connected to switch
33, which toggles between a first position wherein telephone 11 is
coupled to jack 30 through hold circuit 34 and ring detect circuit
35, and a second position, wherein telephone 11 is coupled to data
port 32 through subscriber line interface circuit ("SLIC") 36,
optional CODEC 37, and interface circuit 38. DTMF interface circuit
39, off-hook detection circuit 40 are coupled between jack 31 and
interface 38, while speaker 41 is coupled to interface 38. SLIC 36,
which may be built from discrete components, provides at least the
functionalities of battery feed and hybrid, and more preferably,
also provides overvoltage protection, ringing, supervision, and
test functions, such as current limiting, on-hook transmission,
polarity reversal tip open and loop current detection. Optionally,
call waiting detect circuitry 47 may included apparatus 10 that, if
the user is engaged in an Internet-based telephone call, generates
a call waiting signal that alerts the user of the presence of an
incoming call on the telephone line coupled to jack 30.
[0042] The foregoing components cooperate as follows to achieve the
objectives of the present invention: DTMF interface circuit 39
monitors telephone 11 for input of a predetermined sequence of DTMF
digits, such as "##", "**" or "#*", and reports the occurrence of
digits to interface 38 or an on-board DSP, if present. DTMF
interface circuit may comprise a DTMF detection circuit. Off-hook
detection circuit 40 detects when telephone 11 is off-hook and also
reports that information to interface 38. Interface 38 controls the
position of switch 33 responsive to the information provided by
off-hook detection circuit 40 and DTMF interface circuit 39, and
may be coupled to a serial, parallel or Universal Serial Bus of PC
14. Interface 38 also may comprise a portion of a modem
circuit.
[0043] Accordingly, if apparatus 10 is set to PSTN network calling
for use as a standard analog telephone (hereinafter "A-phone" mode)
as the default, switch 33 will be coupled to jack 30, and the
dialtone from the telephone company will be provided to telephone
11 when it is taken off-hook. If the predetermined sequence of DTMF
digits is not input using the telephone dial pad, the telephone
will remain in A-phone mode.
[0044] If, on the other hand, the user desires to place a
Internet-based telephone call ("I-phone" mode), the user presses
the predetermined sequence of DTMF digits on the telephone dial
pad, which are detected by DTMF interface circuit 39. When those
digits are reported to interface 38, interface 38 (if it includes a
microcontroller) or the central processor unit ("CPU") of PC 14
then instructs switch 33 to toggle to couple telephone 11 to SLIC
36 for use as an I-phone. SLIC 36 may comprise, for example, PEB
4266 integrated circuit available from Infineon Technologies AG,
Munich, Germany, and provides at least the basic analog line
interface functions described hereinabove. The output of SLIC 36 is
passed to coding/decoding ("CODEC") circuit 37 and is digitized for
transmission through interface 38 to the PC.
[0045] As depicted in FIG. 2, apparatus may advantageously be used
to toggle between calls on each of two lines where the user has two
PSTN network lines. It is increasingly common for homes to have two
PSTN network lines, each line having a separate telephone number,
where a first line is coupled to the modem of PC 14 for data
communication and the second line is used for voice communications.
In this instance, apparatus 10 is indirectly coupled to the first
line through the modem of the PC via data port 32, whereas the
second PSTN line is coupled directly to jack 30.
[0046] If the user is engaged in an I-phone mode telephone call
(using PC 14, apparatus 10 and telephone 11), an incoming call on
the second line will be detected by ring detection circuit 35, and
reported to interface 38. Interface 38 alerts the user to the
presence of the call on the second line by generating a
user-perceptible signal, such as a tone or ringing sound on speaker
41, or displaying a message on the display of PC 14. If the user
desires to pick up the incoming call on the second line, the user
inputs the predetermined sequence of DTMF digits using the
telephone dial pad, and apparatus 10 moves switch 33 to couple
telephone 11 to the second line.
[0047] While switched to the second line, the modem of the PC will
put the I-phone call on the first line on hold (up to the time-out
limit of the modem). If the user wishes to toggle back to the
I-phone call, he or she again inputs the predetermined sequence of
DTMF digits, causing apparatus 10 to again change the position of
switch 33. Hold circuit 34, which is per se known, keeps the call
on the second line from being dropped until the user chooses to
again toggle back to the second line and continue that
conversation.
[0048] Referring now to FIG. 3, an implementation of the apparatus
of the present invention suitable for commercialization is
described. Apparatus 50 includes all of components 30-41 described
above with respect to the embodiment of FIG. 2, although in this
embodiment the DTMF interface circuitry is coupled between jack 30
and interface 38, rather than between jack 31 and interface 38.
Accordingly, in the embodiment of FIG. 3, DTMF detection in the
I-phone mode of operation (when switch 33 is coupled to SLIC 36)
may be done either by digital signal processor ("DSP") 42 or the
CPU of the PC.
[0049] Apparatus 50 further includes modem detection circuit 43,
line detection circuit 44, and if interface 38 includes a
microcontroller, EPROM 45 and SRAM 46. Modem detection circuit 43
detects whether the modem of the CPU is active and reports that
information to interface 38. If the modem of the computer is
already active when the handset of telephone 11 is taken off-hook,
interface 38 (or the CPU of the PC) instructs switch to couple
telephone 11 to SLIC 36, on the assumption that an Internet-based
telephone call will be made. Line detection circuit 44 detects
whether a physical line is coupled to jack 30, and if not, puts
apparatus 50 in a default mode of I-phone operation.
[0050] If interface 38 includes a microcontroller, EPROM 45
preferably is provided, for example, for storing a USB identifier,
and SRAM 46 is provided for storing configuration parameters and
firmware for controlling operation of apparatus 50. In a preferred
embodiment, DSP/CODEC comprises the PEB 3265 integrated circuit,
also available from Infineon Technologies AG, in which the DTMF
detection and modem detection are implemented using the second
channel of the integrated circuit.
[0051] Operation of apparatus 50 is similar to that described above
with respect to the embodiment of FIG. 2, in both single PSTN line
and two PSTN line arrangements. When switch 33 is coupled to SLIC
36, components 37 and 42 convert and compress the signals from
analog telephone 11 to digital signals suitable for transmission by
interface 38 to the PC. Components 37 and 42 also convert digitized
speech signals received from PC 14 into analog signals suitable for
transmission to telephone 11. As will of course be understood by
one of ordinary skill, the interface, DSP and CODEC of the present
invention are selected to provide full duplex voice capabilities
during I-phone operation of telephone 11.
[0052] In one preferred embodiment of apparatus 50, interface
controller 38 is a USB controller. Alternatively, interface 38 may
include any controller suitable for transferring digitized data
from apparatus 50 to PC 14 using an available serial or parallel
port of PC 14, or may be omitted entirely.
[0053] Apparatus 50 also preferably is bundled with application
software, executable on PC 14, to load and configure certain
parameters used by apparatus 50. For example, the user may download
configuration parameters stored in SRAM 46 (if present) from PC 14
to configure apparatus 50 to default to either PSTN-based calling
or Internet-based calling when the handset is taken off-hook. Other
parameters, such as the Internet telephony application to be
launched when an Internet-based call is to be made, and the
telephone number to be used to access the Internet gateway, may be
stored in PC 14.
[0054] Referring now to FIG. 4, an alternative embodiment of the
apparatus of FIG. 4 is described, in which the apparatus has the
form factor of an internal card suitable for connection to an
expansion slot on the motherboard of PC 14, e.g., a PCI or
ISA-compatible card. Internal card 55 includes jacks 30 and 31,
switch 33 and components 34-42 as described hereinabove for the
embodiment of FIG. 3. Internal card 55 differs from the embodiment
of FIG. 3 in that edge connector 56 is substituted for jack 32. As
in the previous embodiments, interface circuitry 38 may omit the
microcontroller and instead rely on the CPU of the PC to handle
data transmission to and from internal card 55. Interface circuitry
38 also may comprise a portion of a modem circuit or sound card.
Operation of the internal card is identical to that described for
the embodiment of FIG. 3.
[0055] The apparatus of the present invention advantageously may be
used with a PC modem having a call-waiting feature, such as the
Call-Waiting Modem, offered by the assignee of the present
application, ActionTec Electronics, Inc., Sunnyvale, Calif. Such
modems allow a call-waiting signal generated by a telephone company
to be received by a PC connected to the Internet, and allow the PC
user to accept the incoming telephone call.
[0056] In accordance with the principles of the present invention,
the apparatus of the present invention may be used in conjunction
with a call-waiting modem to toggle an analog telephone coupled to
a PC between an Internet-based telephone call and a PSTN
network-based incoming call, without terminating or dropping either
call. For example, if the user is engaged in an Internet-based call
and receives a call-waiting signal for an incoming PSTN call, the
user may first switch the telephone to A-phone operation by
inputting the predetermined sequence of DTMF digits, and thereafter
(according the call waiting modem instructions) switch to the
incoming call. The user may thereafter switch between the
Internet-based call and the PSTN-based call as desired.
[0057] Referring now to FIG. 5, a flow diagram describing operation
of the embodiments of FIGS. 2 and 3 is described. In FIG. 5, it is
assumed that the apparatus of the present invention is connected to
a data port/bus of PC 14, a previously known analog telephone, and
either the PSTN pass-through jack of the PC modem (as in FIG. 1) or
a separate second line. To initiate a telephone call, the user
lifts the handset at step 60, and at step 61, decides whether to
place a telephone call using either the PSTN network or an
Internet-based telephony service. If the telephone is set to use of
the PSTN network as the default, after obtaining the PSTN dialtone,
step 62, the user dials a desired telephone number to place a call
over the PSTN network, step 63. Upon completion of the call, the
user replaces handset 12 back on telephone 11 to hang up the call
(step 64).
[0058] If, on the other hand, the user desires to place a call
using an Internet telephony service, the user presses the
predetermined sequence of DTMF digits, e.g., "##" on the dial pad
of the telephone, step 65. Modem/DTMF detector 39, detects this
special series of keystrokes, and switch 33 is closed so that the
telephone is coupled to SLIC 36. If, on the other hand, modem
detection circuit 43 detects that the modem is already active, then
switch 33 is set to I-phone mode without the need to input the DTMF
digits.
[0059] SLIC 36 then generates a dialtone, at step 66, which is
preferably audibly different to the user, to let the user know that
the phone has been toggled to Internet-based telephony service.
Off-hook detector 40 also causes interface 38 to initiate a request
to PC 14, step 67, to launch Internet telephony application at step
68. If PC 14 is not already connected to the Internet, launching of
the Internet telephony application will cause PC 14 to dial into
Internet 19 via a local gateway on PSTN 18. In alternative
embodiments, the apparatus may include circuitry and software for
waking up the computer if it is in a powered-down or "sleep"
mode.
[0060] Once the Internet telephone application is running on PC 14,
the user enters the called party's telephone number using dial pad
13 of telephone 11. The dialed number is detected by DTMF interface
circuit 39, and digitized data corresponding to the DTMF tones is
passed to PC 14 via interface 38. This data is then used by the
Internet telephony application and server-based application at the
Internet telephony service provider (part of Internet 19) to
establish a VOIP connection, at step 70, through Internet 19 with
the called party's telephone 20 (see FIG. 1).
[0061] When the call is answered, either by the called party or his
or her answering machine, the user speaks into the mouth piece of
handset 12 at step 71. The analog voice signal is processed by SLIC
36, at step 72, and converted to digital data using DSP 42 and
CODEC 37, at step 73. The digitized and compressed voice signal is
passed to PC 14 via interface 38 at step 74 for transmission over
Internet 19 to called telephone 20. Speech from the called party,
step 75, may be simultaneously transmitted via Internet 19 to PC
14. This digitized data then is passed to DSP 42 and CODEC 37, and
converted for transmission to telephone 11, at step 76. As will of
course be understood, the apparatus of the present invention
supports a full duplex mode of voice communication using the
Internet.
[0062] The call continues with voice communications between the
user and called party being transmitted as described at steps 71 to
76 until the call is completed, step 77. When the call has been
completed, the user hangs up, step 78, and off-hook detection
circuit 41 signals interface controller 39 to request that PC 14
terminate the Internet telephony application running on PC 14.
[0063] Referring now to FIG. 6, operation of the apparatus of the
present invention with a single PSTN line and call waiting modem is
described. In this case, the user has already lifted the handset,
step 80, and established an Internet-based telephone call, step 81,
in accordance with the steps described in FIG. 5. At step 82,
during the pendency of the Internet-based call, the user receives a
call waiting signal from PSTN 18, indicating an incoming call. The
call waiting modem detects the call waiting signal and alerts the
user to the presence of the incoming call, at step 83, with a
user-perceptible signal, e.g., by generating an audible tone using
speaker 41 or the speaker on the internal modem of PC 14, or
displaying a message on the display of PC 14.
[0064] At step 84, the user presses "##" on dial pad 13 of
telephone 11 to toggle the telephone from the Internet-based call
to the incoming call. In accordance with the call waiting modem
operating instructions, the user notifies the telephone company
that the incoming call will be accepted, step 85. At step 86, the
telephone is connected to the incoming call, and the modem puts the
Internet-based call on hold (up to its predetermined time-out
period). If the user completes the incoming call within the
time-out interval of the modem, the user may then press "##" again
on the telephone dial pad to return to the Internet-based call, at
step 87. Once the Internet-based call is completed, the call is
terminated, at step 88, as described hereinabove with respect to
call termination in FIG. 5.
[0065] Referring to FIG. 7, operation of the apparatus of the
present invention in a two line arrangement is now described. In
this case, a first telephone network line from the PSTN network,
having a first telephone number, is coupled to the modem of PC 14,
and a second telephone network line from the PSTN network, having a
second telephone number, is coupled to jack 30. To place a
telephone call using the Internet, the user lifts handset, step 90,
and establishes a telephone call on the first line at step 91 in
accordance with the steps 65-77 of FIG. 5.
[0066] If the user receives an incoming call on the second line,
ring detect circuit 35 informs interface 38, which in turn notifies
the user of the presence of the second call via speaker 41. The
user then may press the predetermined sequence of DTMF digits on
the telephone dial pad, thereby causing switch 33 to couple the
telephone to jack 30 to receive the incoming call on the second
line, step 93. When the call on the second line is completed, the
user toggles the phone to Internet-based mode, by pressing "##" on
the telephone dial pad, and returns to the Internet call
previously-established on first line, step 94.
[0067] If, on the other hand, the user receives an incoming call on
the first line (and subscribes to a call waiting service and has a
call waiting modem), then the user can accept the incoming
Internet-based call in accordance with steps 85-87 of FIG. 6.
Because switch 33 is already set for Internet-based telephony
service, the user need not input the predetermined sequence of DTMF
digits.
[0068] Still referring to FIG. 7, the user instead may choose to
place a telephone call using the PSTN network. In this case, the
user lifts the handset, step 90, and establishes a telephone call
on the second line, step 91, in accordance with the steps 62 and 63
of FIG. 5. If the user receives an incoming call on the first line,
interface 38 notifies the user of the presence of the incoming call
via speaker 41. The user then may press the predetermined sequence
of DTMF digits on the telephone dial pad, to cause switch 33 to
couple the telephone to SLIC 36 to receive the incoming Internet
call on the first line, step 95. Hold circuit 34 ensures that the
PSTN-based call on the second line is not dropped while the
Internet call is accepted. When the call on the first line is
completed, the user toggles the phone to PSTN-based mode, by
pressing "##" on the telephone dial pad, and returns to the PSTN
call previously established on second line, step 96.
[0069] Referring now to FIGS. 8A to 8C, use of the apparatus of the
present invention in contexts other than analog-based modems is
described. In FIG. 8A, the apparatus of the present invention is
coupled to telephone 11 and PC 14. PC 14 is coupled to PSTN 18 and
Internet 19 via DSL modem 100, cable 111 and splitter 112. The
inventive apparatus also is coupled to PSTN network 18 using
standard telephone jack 114 and splitter 112. Operation of the
system depicted in FIG. 8A is similar to that described for the
embodiments of FIGS. 1-4, except that Internet-based telephone
calls are routed through PC 14 and DSL modem 100. As will of course
be understood by one of ordinary skill, DSL modem 100 may be a
splitter-less DSL modem, in which splitter 112 is omitted and
microfilters optionally are instead installed on the analog
telephones to filter out transients induced by the analog
telephone.
[0070] In FIG. 8B, the inventive apparatus is coupled to telephone
11 and PC 14. PC 14 is coupled to Internet 19 via cable modem 115
and cable line 116. Cable modem 115 is connected to the Internet
via a gateway accessible to the cable modem head end. The apparatus
also is coupled to PSTN network 18 using standard telephone jack
117. Operation of the system depicted in FIG. 8B is similar to that
described for the embodiments of FIGS. 1-4, except that
Internet-based telephone calls are routed through PC 14 and cable
modem 115.
[0071] In FIG. 8C, the inventive apparatus again is coupled to
telephone 11 and PC 14. PC 14 is coupled to PSTN 18 and Internet 19
via ISDN modem 118, ISDN line 119 and jack 120. The apparatus also
is coupled to PSTN network 18 using jack 120. Operation of the
system depicted in FIG. 8C again is similar to that above-described
embodiments, except that Internet-based telephone calls are routed
through PC 14 and ISDN line 119.
[0072] Referring now to FIGS. 9A and 9B, a second embodiment of the
apparatus of the present invention is described. This embodiment
combines the switching circuitry of the present invention into a
specialized telephone suitable for placing and receiving either
Internet-based or PSTN-based telephone calls, including toggling
between such calls, simply by pressing a button. Telephone 130
illustratively comprises base station 131 that communicates with
wireless handset 132 using technology that is per se known. As is
conventional, each of base station 131 and handset 132 includes
dial pad 133. In accordance with the principles of the present
invention, each of base station 131 and handset 132 includes button
134 for toggling the telephone between PSTN and Internet-based
telephone service. Telephone 130 also preferably includes LEDs 135
that indicate whether the phone is set for PSTN or Internet-based
telephony service.
[0073] In FIG. 9B, a schematic diagram of the internal components
of base station 131 of telephone 130 is described. Telephone 130
includes dial pad 133, button 134, analog telephone circuit 136,
switching circuit 137, microprocessor 138 and modem 139. Telephone
130 also comprises RF circuitry (omitted for clarity in FIG. 9B),
which is per se known, so that handset 132 can communicate with
base station 131.
[0074] Analog telephone circuit 136 comprises previously known
circuitry for generating analog telephone signals from voice, and
for converting analog telephone signals to audible speech.
Microprocessor 138 is programmed with suitable software stored in
non-volatile memory (not shown), such as SRAM and/or EEPROM, and is
capable of packaging digitized speech signals for transmission over
the Internet using a VOIP protocol. Modem 139 is coupled to
microprocessor 138 for transmitting the data received from
microprocessor 138, and for transmitting received data from the
Internet back to microprocessor 138. Preferably, modem 139 includes
a call waiting feature, so that the modem can alert the user to the
presence of an incoming call.
[0075] In accordance with the principles of the present invention,
switching circuit 137 comprises selected circuits employed in the
embodiment of FIGS. 2-4, including at least switch 33 and
subscriber line interface circuit 36, as described hereinabove.
Switching circuit 137 is coupled to button 134 to receive a signal
from button 134 that changes the state of the switch in switching
circuit 137. A switch (like switch 33 in the embodiments of FIGS. 2
to 4) within switching circuit 137 moves between a first position
wherein analog telephone circuit 136 is coupled to jack 140, for a
PSTN network call, and a second position, wherein analog phone
circuit 136 is coupled to jack 140 through switching circuit 137,
microprocessor 138 and modem 139. In the second position, telephone
130 may be used to place a telephone call using an Internet-based
telephony service, i.e., in I-phone mode.
[0076] In accordance with one aspect of the present invention,
telephone 130 permits a user to toggle between an Internet-based
telephone call and a PSTN network telephone call. Specifically,
because telephone 130 preferably incorporates call waiting modem
circuitry, it can detect a call waiting signal sent from the
telephone company, and alert the user to the presence of the
incoming call, e.g., using a speaker on modem 139. The user may
then depress button 134 to cause switching circuit 137 to couple
the analog telephone circuit to jack 140 to receive a PSTN-based
telephone call. The user may then, for example, depress the hook to
send a flash signal to the telephone company to indicate that the
incoming call is to be coupled to the line. During that call, or
after that call is completed, the user may again press button 134
to toggle the telephone call to the Internet-based telephone
mode.
[0077] Referring now to FIGS. 10A and 10B, a third alternative
embodiment of the apparatus of the present invention is described.
Module 150 illustratively is coupled to standard analog telephone
151 by cable 152, and coupled to the PSTN network via cable 153.
Module 150 permits telephone 151 to be selectively used in either
A-phone mode (i.e., to place telephone calls via the PSTN network)
or I-phone mode (i.e., to place telephone calls via the Internet),
and includes optional button 154 that permits the telephone to be
toggled between the two modes of operation. Indicator LEDs 155
illuminate to display the status of module 150 as operating in
either A-phone or I-phone mode. Optional display screen 156 may be
used to display the telephone number dialed using telephone 151, to
confirm data input to module 150 via the dialpad of telephone 151,
or other functions, such as displaying caller ID.
[0078] With respect to FIG. 10B, module 150 includes jack 157,
switching circuitry 158, microprocessor 159, modem 160 and jack
161. Jack 157 receives a standard connector (e.g., RJ-11 plug) on
cable 152. Switching circuitry 158 includes selected elements of
the embodiments of FIGS. 2-4, including at least switch 33 and
subscriber line interface circuit 36 with the basic functionality
described hereinabove with respect to FIG. 2. Microprocessor 159
includes associated hardware (not shown), such as SRAM and/or EPROM
memory for storing configuration parameters and program
instructions, including instructions for establishing a connection
to the Internet via modem 160 and transmitting and receiving data
in accordance with a VOIP protocol. Modem 160 includes standard
modem circuitry and firmware, and in addition, may include call
waiting detection circuitry and/or software.
[0079] Module 150 provides the same functionality as the two
embodiments described hereinabove with respect to FIGS. 2-4 and 9A
and 9B, by allowing a user to place a telephone call in either
A-phone mode or I-phone mode, and switch between active calls.
Whereas the embodiments of FIGS. 1-4 required that the user connect
the apparatus of the present invention to both a computing device
and an analog telephone, the embodiment of FIGS. 9A and 9B instead
provides a fully integrated solution, where the necessary elements
of the computing device, the switching circuitry, and analog
telephone circuit are incorporated in a single unit. The embodiment
of FIGS. 10A and 10B provides an intermediate, partially-integrated
solution by combining the switching circuitry of the present
invention with the necessary elements of the computing device.
Accordingly, the embodiment of FIGS. 10A and 10B permits the user
to employ a standard analog telephone, but without the need to
couple the module to a previously known PC.
[0080] Operation of module 150 is as described hereinabove with
respect to the previously described embodiments and FIGS. 5 through
7. In particular, the user places a call by picking up the handset
of telephone 151. If it is desired to place a PSTN-based telephone
call (and that is selected as the default mode of operation of
module 150), the user simply dials the called party's telephone
number. On the other hand, if the user desires to use telephone 151
to place an Internet-based call, the user presses button 154 to
place the telephone in I-phone mode. Microprocessor is awakened and
establishes a connection via modem 160 to an Internet telephony
service. Once the Internet connection is established, the user
inputs the called party's number, and continues with the call in
accordance with the operating instructions for the Internet
telephony service.
[0081] If modem 160 includes a call waiting feature, it may detect
a call waiting signal generated by the telephone company and alert
the user to the presence of the incoming call. The user then may
accept the incoming call, for example, by inputting a predetermined
series of DTMF digits, or by pressing a button. As for the
preceding embodiments, during the pendency of the second call, the
user may toggle back and forth between the calls using button
154.
[0082] Although specific embodiments of the present invention have
been described above in detail, it will be understood that this
description is merely for purposes of illustration. Further
variations will be apparent to one skilled in the art in light of
this disclosure, and all such variations are intended to fall
within the scope of the appended claims.
* * * * *