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VP530 and incorrect answer on initial INVITE with t.38 - Printable Version

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+--- Thread: VP530 and incorrect answer on initial INVITE with t.38 (/showthread.php?tid=2122)



VP530 and incorrect answer on initial INVITE with t.38 - lx2006 - 07-23-2014 06:02 PM

Dear support,

Callee(22222) - Yealink VP530
Firmware Version 23.70.0.40
Hardware Version 23.5.1.201.18.0.8

Caller(11111) - Softphone Kapanga with enabled audio,video,t38 (t.38 in initial INVITE)

1. Caller makes call to callee
2. After answering call drops

Initial INVITE SDP from caller
INVITE sip:11111@192.168.1.10 SIP/2.0
....
v=0
o=22222 1406098068 1406098115 IN IP4 192.168.1.132
s=Kapanga [1406098068]
c=IN IP4 192.168.1.132
t=0 0
m=audio 5106 RTP/AVP 0 8 101
a=rtpmap:0 PCMU/8000
a=sendrecv
a=rtcp:5107
a=maxptime:20
a=ptime:20
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
m=video 5108 RTP/AVP 34
a=rtpmap:34 H263/90000
a=fmtp:34 QCIF=2
a=sendrecv
a=rtcp:5109
m=image 5106 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval:0
a=T38FaxTranscodingMMR:0
a=T38FaxTranscodingJBIG:0
a=T38FaxMaxBuffer:200
a=T38FaxMaxDatagram:72
a=T38FaxUdpEC:t38UDPRedundancy
a=T38FaxRateManagement:transferredTCF

SDP: After Answered by callee
SIP/2.0 200 OK
...
v=0
o=- 20021 20021 IN IP4 192.168.1.160
s=SDP data
c=IN IP4 192.168.1.160
t=0 0
m=audio 11790 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=sendrecv
a=fmtp:101 0-15
a=rtpmap:101 telephone-event/8000
m=video 11792 RTP/AVP 34
a=rtpmap:34 H263/90000
a=fmtp:34 QCIF=2
a=sendrecv
m=image 11790 udptl 0
a=rtpmap:0 PCMU/8000


Why VP530 answers in sdp image section with audio codec?
This device doesn't support Fax Undecided


RE: VP530 and incorrect answer on initial INVITE with t.38 - Bryan Nelson - 07-31-2014 07:32 AM

Looks like a default behavior in the sip stack that was not removed. I take it this is giving you trouble, since the Caller then assumes it is a fax call?

Though this phone doesn't support fax like you said, so why the fax invites?