1. SIP And DTMF SIP WG 48th IETF July 31-August 4, 2000 Bert Culpepper, Skip Cave

2. 48th IETFSIP WG2 DTMF Related Proposals The SIP INFO Method –draft-ietf-sip-info-method-04.txt –Draft describes the use of the SIP INFO Method for mid-call signaling along the SIP signaling path. DTMF is one data type described. Sample Uses of SIP INFO with Varying Reliability Needs –draft-kuthan-sip-infopayload-00.txt (expired) –Draft describes mid-session signaling and reliable in-order delivery using the SIP INFO method. Describes DTMF digit strings in INFO message bodies. Suggests MGCP/Megaco MIME content support in Gateway Controllers.

3. 48th IETFSIP WG3 DTMF Transmission Techniques Contained in Media (RTP Stream) –Doesn’t work with compressed media. –Requires “ports” in service platforms. Special Encoding in RTP (RFC 2833) –Can be sent separate from other media (Supports 3pcc). –Requires RFC 2833 encoder/decoder. RFC 2833 Encoded Data Using INFO Method –Can be sent along the call signaling path (Supports 3pcc). –Requires RFC 2833 encoder/decoder. DTMF Using INFO Method (draft-choudhuri-sip-info-digit-00.txt) –Can be sent along the call signaling path (Supports 3pcc). –Text-based encoding of DTMF. –No “out-of-order” issues. –Draft goes beyond DTMF transmission by describing collection attributes to be used by a client.

4. 48th IETFSIP WG4 DTMF Transmission Techniques (cont.) MGCP/Megaco-Based Event Detection and Reporting Using INFO Method (draft-culpepper-sip-info-event-00.txt) –Can be sent along the call signaling path (Supports 3pcc). –MGCP/Megaco text-based encoding of DTMF. –No “out-of-order” issues. –Specific to networks containing MGCP/Megaco-based Media Gateways and Media Gateway Controllers. –Goes beyond DTMF transmission by describing MGC enabled event detection and reporting at the MG. Leverages MGCP/Megaco compliant DTMF collection and reporting capabilities.

5. 48th IETFSIP WG5 Preferred Support Mechanism in SIP Recent discussions on the SIP list indicate preferred method for DTMF transmission is RFC 2833 encoded packets transported via RTP. However, it’s still not a “closed” issue. Issues to Consider DTMF in a packet network is application control. Session-related Services Platforms require user interaction independent of the primary media. (When voice recognition is not employed by the service.) SIP is the IETF protocol currently carrying telephony signaling around a packet network (there is MGCP/Megaco at the edges). And in this role, mid-call signaling in SIP can support carrying today's PSTN enhanced services. However, other protocols exist for control and event reporting capabilities.