SYSTEM PREVENTING DOUBLE DIGIT DETECTION CAUSED BY IN-BAND DUAL-TONE MULTI-FREQUENCY SIGNALING AND METHODS THEREOF
A T2P (TDM to packet) delay buffer is provided. The delay buffer can prevent double digit detections caused by in-band DTMF leak when out-of-band DTMF is used. The T2P delay buffer is initialized with an audio pattern that represents silence in a configurable amount of delay. When a DTMF digit is detected, the system can stop taking the voice payload from the T2P delay buffer and start injecting RFC4733 RTP packets into the RTP stream at a pre-configured rate. The RFC4733 DTMF RTP packets continue to be injected into the RTP stream until the DTMF digit stops. Once the end of the DTMF digit is detected, the content of the T2P delay buffer can be discarded and the T2P delay buffer is reinitialized with an audio pattern that represents silence in a configurable amount of delay. After the T2P delay buffer is reinitialized, the voice packetization can be continued.
1 . A method for preventing double digit detection in a downstream circuit-switched network caused by in-band dual-tone multi-frequency (DTMF) leaks when a voice path goes through a packet-switched network and out-of-band-DTMF is used within the packet-switched network, the method comprising:
receiving audio;
packetizing the audio into a delay buffer in a time division multiplexer to packet network direction;
discontinuing packetization of the audio when a DTMF digit is detected;
injecting DTMF signaling packets for the DTMF digit until the DTMF digit stops;
discarding contents within the delay buffer;
filling the delay buffer with a silence pattern; and
restarting packetization of the audio.
2 . The method of claim 1 , comprising initializing the delay buffer.
3 . The method of claim 1 , comprising acquiring the audio from a circuit-switched network.
4 . The method of claim 1 , comprising continuing with packetizing the audio when the DTMF digit is absent otherwise discontinuing packetization.
5 . The method of claim 1 , wherein discarding contents within the delay buffer comprises removing an in-band DTMF leak within the delay buffer.
6 . The method of claim 1 , wherein filling the delay buffer with the silence pattern comprises adding a configurable amount of delay.
7 . The method of claim 6 , comprising filling a remaining amount of the configurable amount of delay into at least one additional packet outside of the delay buffer.
8 . The method of claim 6 , comprising determining a time to detect the DTMF digit to add the configurable amount of delay.
9 . A device comprising:
at least one processor; and
a memory operatively coupled to the processor, the memory storing program instructions that when executed by the processor, causes the processor to:
receive audio;
packetize the audio into a T2P delay buffer;
discontinue packetization of the audio when a DTMF digit is detected;
inject DTMF signaling packets for the DTMF digit into a packet network until the DTMF digit stops;
discard content of the T2P delay buffer;
place a delay into the T2P delay buffer by filling it with silence pattern;
restart packetization of the audio.
10 . The device of claim 9 , wherein the delay placed into the T2P delay buffer is configurable and dependent on detection of the DTMF digit.
11 . The device of claim 9 , wherein the delay is zero (0) milliseconds when the DTMF digit detection requirement is absent.
12 . The device of claim 9 , wherein the delay is dependent on a time to detect the DTMF digit.
13 . The device of claim 9 , wherein additional delay is placed into at least one packet outside of said the T2P delay buffer.
14 . The device of claim 9 , wherein the T2P delay buffer holds a minimum number of packets to accommodate a maximum amount of the delay.
15 . A system comprising:
a time division multiplexer to packet side delay buffer for preventing double digit detection caused by in-band DTMF leak when out-of-band DTMF is used, wherein packetization of audio is stopped when a DTMF digit is detected, DTMF signaling packets injected into a stream for the DTMF digit, packets within the delay buffer discarded and a configured amount of silence added to the delay buffer.
16 . The system of claim 15 , wherein the DTMF signaling packets are injected into the stream until the DTMF digit stops.
17 . The system of claim 15 , wherein the configured amount of silence is dependent on a detection time of the DTMF digit.
18 . The system of claim 15 , wherein the DTMF digit is detected when the audio represents the DTMF digit for more than forty (40) milliseconds.
19 . The system of claim 15 , wherein a new DTMF digit is detected when the audio is interrupted between ten (10) milliseconds to twenty (20) milliseconds.
20 . The system of claim 15 , wherein the packets injected into the stream for the DTMF digit are RFC4733 DTMF.