Robust DTMF detection in an unreliable voice-over-IP (VoIP) environment

摘要

A method to discriminate a signal as a DTMF digit is operative in a service provider having a VoIP-based media server. The media server accepts both in-band DTMF and RTP telephone events. A digit detection module receives as input a data stream that may include one or more DTMF digits. The module processes the input data stream and provides, as output, an indication of what digit(s) have been detected and from what source (e.g., in-band audio, an RTP 2833 telephone event, of both). The output is then further processed by a discrimination algorithm to make a final digit determination. If RTP telephone events are detected, the algorithm prefers them and ignores in-band DTMF until the call ends or the media is re-negotiated. The approach detects when duplicate digits of differing types are initially received and only accepts one of them, regardless of spacing or duration.

主权项

1. A media server connectable to at least an Internet telephony carrier, the media server comprising:
a switch adapted to connect telephony devices during an outbound call; processor coupled to the switch; and memory, wherein the memory has stored therein instructions that, when executed by the processor, cause the processor to:
receive a data stream from the Internet telephony carrier during the outbound call, wherein the received data stream includes an in-band dual-tone multi-frequency (DTMF) event data and a real-time transport protocol (RTP) event data;identify the Internet telephony carrier as being configured to send in-band DTMF event data;discard the in-band DTMF event data from the data stream; andidentify a user input based on the modified data stream, wherein in response to the identified user input, the switch establishes the connection of the telephony devices.