hi there

we got a weird problem on our ser when dealing with multiple media descriptions in SDP packets:

the INVITE comes from a SIP-enabled TDM-switch and looks like that (notice 3(!) different media descriptions, but pointing to the same port):

(just media-descriptions shown for brevity):

Media Description, name and address (m): audio 17728 RTP/ AVP 0 8 4 18 2 101 Media Attribute (a): fmtp:101 0-15 Media Attribute (a): rtpmap:101 telephone-event/8000 Media Description, name and address (m): audio 17728 RTP/ AVP 97 Media Attribute (a): rtpmap:97 /8000 Media Attribute (a): sendonly Media Description, name and address (m): audio 17728 RTP/ AVP 97 Media Attribute (a): rtpmap:97 /8000 Media Attribute (a): recvonly

when the SER receives this packet it looks up the client (b-number) and recognizes it is behind a NAT - so mediaproxy stuff is done (notice SER/mediaproxy generating 3(!) different(!) ports for the media-descriptions):

(same brevity here):

Media Description, name and address (m): audio 16014 RTP/ AVP 0 8 4 18 2 101 Media Attribute (a): fmtp:101 0-15 Media Attribute (a): rtpmap:101 telephone-event/8000 Media Description, name and address (m): audio 16016 RTP/ AVP 97 Media Attribute (a): rtpmap:97 /8000 Media Attribute (a): sendonly Media Description, name and address (m): audio 16018 RTP/ AVP 97 Media Attribute (a): rtpmap:97 /8000 Media Attribute (a): recvonly

the client (a sipura 2100/1001) now sends media to the last specified port (16018 in our case) while the audio from the switch goes to 16014 - resulting in mediaproxy not being able to connect the two of them ... and we sit there with neither in- nor outbound audio ...

how do i get mediaproxy/SER to send only one port to the client, just like the switch initially did?

any clues?

mit freundlichen Grüßen / with best regards

Gerd Feiner Leitung IP-Dienste

Kabelfernsehen München ServiCenter GmbH & Co. KG Abt. Mediaport Medienallee 24 85774 Unterföhring

T: +49 89 95083 243 F: +49 89 95083 132 E: g.feiner@cablesurf.de W: www.cablesurf.de