Normally, DTMF digits are communicated over the RTP (Media) stream using either inband (audio) or payloads (RFC2833). The problem in this case is that, with SIP, the media flow is between endpoints (the caller/called and Blueworx Voice Response) whereas the information needs to be sent to or received from a switch. The only way to do this is using the SIP Signalling path and the only defined way to do this is by using the SIP INFO method defined by RFC2976.
The SIP INFO Method is controlled by Blueworx Voice Response using a System Parameter in the VoIP DTEA and DTNA Media parameter group. Normally, the DTMF method is limited to RTP methods only (inband/payload). However, using the System Parameter Outbound DTMF Method Override, it is possible to force the DTMF transmission type to be inband, payload or (the new option) SIP Info method. In this case, any State Table ‘Dial’ action will cause DTMF keys to be sent using the SIP INFO method. Similarly, using the System Parameter Inbound DTMF Method Override, it is possible to enable the DTMF reception method of SIP Info. In this case, the State Table 'GetData' action will allow collection of DTMF keys sent using the SIP INFO method.
SIP INFO Method is implemented for DTNA only.