Method and system for transmitting a DTMF signal with compressed voice in a packet switching network

A source node for use in a packet switching communication network having a plurality of nodes interconnected with transmission links, said source node comprising:

• a Dual Tone MultiFrequency (DTMF) detector for detecting candidate DTMF signals in a received signal comprising voice or DTMF signals wherein each DTMF signal has two signal components, each at a respective frequency;
• a filter for modifying each detected candidate DTMF signal by removing the signal component at one of the two frequencies defining said detected candidate DTMF signal;
• a packet generator for generating packets representing either voice signals or modified candidate DTMF signals;
• a transmit interface for transmitting generated packets into the network;
• compression logic for compressing the voice signals and the modified candidate DTMF signals prior to the generation of packets including such signals;
• a DTMF verification logic component for determining whether a candidate DTMF signal is a true DTMF signal;
• and
• packet generating logic for generating a packet representing the true DTMF signal;
• wherein said packet representing a valid DTMF signal comprises a packet identifier field for identifying the packet as representing a DTMF signal, a key field for identifying the pair of DTMF signals comprising the DTMF signal, a type field for identifying the tone-on and tone-off periods of the DTMF signal, and two energy fields representing, respectively, the energy level of the signal components at one of the two frequencies.

A method of receiving data for use in a receiving node in a packet switching communication network having a plurality of nodes interconnected with transmission links, comprising the steps of:

• receiving an input signal comprising compressed voice signals and packets representing DTMF signals having two signal components, each at a respective frequency;
• detecting a packet representing DTMF signals in the received input signal;
• reconstituting a DTMF signal represented by said packet;
• and,
• transmitting a reconstituted DTMF signal;
• wherein the step of reconstituting includes decompressing voice packets and packets representing DTMF signals, and wherein said packets representing DTMF signals comprise
• a packet identifier field for identifying the packet as representing a DTMF signal;
• a key field for identifying the pair of DTMF signal components comprising the DTMF signal;
• a type field for identifying the tone-on and tone-off periods of the DTMF signal;
• and two energy fields, wherein each energy field represents a level of energy for a signal components at a respective frequency.

A destination node for use in a packet switching communication network having a plurality of nodes interconnected with transmission links, said destination node comprising:

• an interface unit for detecting compressed DTMF packets in a received signal;
• a DTMF generator for creating reconstituted DTMF signals from said DTMF packets, the reconstituted DTMF signals representing modified DTMF signals;
• an interface for transmitting the reconstituted DTMF signals, wherein said compressed DTMF packets in a received signal comprise compressed voice signals, compressed DTMF packets, or both;
• and
• decompression logic means for decompressing the voice signals and DMTF signal generation logic for reconstituting the DTMF signals prior to transmitting the voice signals and DTMF signals;
• wherein the packet representing a valid DTMF signal comprises a packet identifier field for identifying the packet as representing a DTMF signal, a key field for identifying the pair of DTMF signals comprising the DTMF signal, a type field for identifying the tone-on and tone-off periods of the DTMF signal, and two energy fields representing, respectively, the energy level of the signal components at one of the two frequencies.