According to the RFC, the Allow-Events header is specifically used to convey events that a UA can support using the SUBSCRIBE method. Typically we’ll see KPML or Presence as a supported Allow-Event value, which makes sense since both of those events are initiated through SUBSCRIBE/NOTIFY transactions. I’m looking through sets of trace files where I know RTP-NTE is negotiated and have found multiple instances where DTMF was negotiated successfully (to RTP-NTE) without including telephone-events in the Allow-Events header.
What type of issues are you seeing with ReINVITEs? From: cisco-voip [mailto:[email protected]] On Behalf Of Ed Leatherman Sent: Friday, July 08, 2016 9:18 AM To: Cisco VOIP <[email protected]> Subject: [cisco-voip] SIP protocol question Happy Friday! This is probably a dumb basic question but my google-fu is failing me. What exactly is the "telephone-event" event package used for in the allow-events: header? Must it be present? I have been assuming it had to do with rtp-nte but that seems wrong since that's negotiated in the SDP. I'm trying to integrate with our associated Medical Center with a SIP Trunk out of CUBE (IOS 15.4(3)M3) - they are running a mish-mash of Siemens PBX/SIP/Call Center stuff on their end. I'm having some weird stuff happen with reinvites when their system(s) transfer the call around and I'm trying to nail down everything I find that i'm not sure of... in one of the transactions the telephone-event is missing out of the allow-events in the invite. Thanks! -- Ed Leatherman
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