Hi,
I have following setup:
Cisco Call Manager Express 11 on 4331 router (10.192.35.1)
Microsoft Skype for Business 2015 server (10.192.35.4)
I created gateway and trunk configuration on SfB side, I created voice dial plans on CME side:
dial-peer voice 22 voip
description Outgoing dial-peer to Lync
destination-pattern 92..
notify redirect ip2pots
session protocol sipv2
session target ipv4:10.192.35.4:5068
session transport tcp
voice-class codec 1
dtmf-relay rtp-nte
fax rate disable
fax protocol pass-through g711alaw
no vad
!
dial-peer voice 21 voip
description Incoming dial-peer from Lync
answer-address 92..
b2bua
session protocol sipv2
session target ipv4:10.192.35.4:5068
session transport tcp
voice-class codec 1
voice-class sip dtmf-relay force rtp-nte
dtmf-relay rtp-nte
no vad
When I call from Cisco to SfB, calls work just fine.
When I call from SfB to Cisco, Cisco phone is ringing, but after I pickup, call is disconnected. I studied Cisco logs from Cisco side and sent them to Cisco support, they said the call was disconnected from SfB side. SfB side is sending SIP BYE less than a second after call is active, and also, voice is one-way.
I started Wireshark - and Wireshark shows INVITE, RINGING, then RTP voice stream starts flowing from Cisco side, then there is something wierd, SfB opens STUN, RTCP, and CLASSI_ binding request (and I don't see that Cisco responds to that), and there is then RTCP Receiver Report Goodbye packet after which SfB closes communication and sends SIP BYE. I don't see that Cisco responds to any RTCP packets.
Does anyone know what is the problem here?
