US 6,259,691 B1 · System and method for efficiently transporting dual-tone multi-frequency/multiple frequency (DTMF/MF) tones in a telephone connection on a network-based telephone system

Abstract

A method and system in a network telephony system for transporting audio signals with lower delay when DTMF is not present. The method of transporting audio signals determines whether DTMF signals are included in the audio signal, or are likely to be transported according to the called or calling parties. A delay is imposed in the audio when DTMF signals are sensed or determined to be present as indicated by the calling party, the destination telephone number, the called party, and various other indicators. A timer may be used to trigger a reduction and elimination in the audio delay after an initial period in the call for calls in which DTMF signaling is used for an initial period of the call. The timer may also trigger the reduction and elimination in the audio delay when no DTMF signals have been received after a period of time. The system uses a DTMF detector to sense DTMF signals in the audio signal and to signal the delay generator to impose a delay in the audio stream. The delay generator may impose the delay by elongating the time between talk-spurts or by inserting fill packets in the audio stream. The delay may be removed from the audio stream when DTMF is not likely to be present.

Claims34

Dependent claims

In a network-based telephone system comprising a first and second telecommunications device, the first telecommunications device being operable to generate voice signals and dual-tone multi-frequency (DTMF) signals in an audio signal, the first and second telecommunications devices being connected to a packet-based network, a method for efficiently transmitting the audio signal to the second telecommunications device, the method comprising the steps of:

detecting if the audio signal includes at least one DTMF signal;
generating an audio delay when the audio signal includes the DTMF signal;
creating an audio stream using the audio signal;
transporting the audio stream without the audio delay when the audio signal does not include the DTMF signal;
when the audio stream includes the DTMF signal, creating a separate DTMF stream using the DTMF signals in the audio signal;
transporting the DTMF stream and the audio stream on the packet-based network with the audio delay;
and
decoding the DTMF and audio streams from the packet-based network to create a received audio signal, and to transmit the received audio signal to the second telecommunications device.

5 more elements

A network-based telephone system for connecting a first telecommunications device and a second telecommunications device over a packet-based network, the system comprising:

a first gateway comprising:
a telephone network interface for receiving an audio signal from the first communications device via a public switched telephone network;
a call process driver for creating a virtual call connection for communicating the audio signal, the call process driver comprising a prompter for prompting a user of the first telecommunications device for call setup information, the call setup information including a destination number and whether the destination number is of a type that includes DTMF signals during an initial period of the virtual call connection;
a dual-tone multi-frequency (DTMF) and audio controller for removing the DTMF signal from the audio signal and for generating a delay in the audio signal;
an audio encoder for creating an audio stream for transporting the audio signals over the packet-based network;
and
a network interface for converting the audio stream into an audio session and transporting the audio stream over the packet-based network;
and
a second gateway for receiving the DTMF and audio sessions, the second gateway being communicably connected to the second communications device via a second telephone network interface, the second gateway being operable to translate the audio session into a received audio signal and to transmit the received audio signal to the second communications device.

6 more elements

A network-based telephone system for connecting a first telecommunications device and a second telecommunications device over a packet-based network, the system comprising:

a first gateway comprising:
a telephone network interface for receiving an audio signal from the first communications device via a public switched telephone network;
a call process driver for creating a virtual call connection for communicating the audio signal, the call process driver comprising a prompter for prompting a user of the first telecommunications device for call setup information, the call setup information including a calling party number and whether the calling party number is of a type that includes DTMF signals during an initial period of the virtual call connection;
a dual-tone multi-frequency (DTMF) and audio controller for removing the DTMF signal from the audio signal and for generating a delay in the audio signal;
an audio encoder for creating an audio stream for transporting the audio signals over the packet-based network;
and
a network interface for converting the audio stream into an audio session and transporting the audio stream over the packet-based network;
and
a second gateway for receiving the audio sessions, the second gateway being communicably connected to the second communications device via a second telephone network interface, the second gateway being operable to translate the audio sessions into a received audio signal and to transmit the received audio signal to the second communications device.

6 more elements

Dependencies are inferred from the claim text.

System and method for efficiently transporting dual-tone multi-frequency/multiple frequency (DTMF/MF) tones in a telephone connection on a network-based telephone system

Life of this patent

System and method for efficiently transporting dual-tone multi-frequency/multiple frequency (DTMF/MF) tones in a telephone connection on a network-based telephone system

Life of this patent

Abstract

Claims34