Showing results for 
Search instead for 
Did you mean: 
Walkthrough Wednesdays

Lync and CUBE Sip trunk - PSTN calls disconnection

Hi guys,

I've this scenario:

Lync 2013 (standalone - only Mediations server) <---- SIP TRUNK ----> CUBE (ISR 4400) <----SIP TRUNK ---> CUCM 11.5


- On Lync I use Skipe Bus. client - DN:14xx, - On CUCM I use Cisco 7821 - DN - 13xx
- Cisco CUBE has a QSIG ISDN trunk to PSTN
So when Lync client calls Cisco IP Phone all works fine, RTP it's on: signaling is SIP purely, on CUBE there are two voip SIP dial peer;
The problem happens when Lync client call ISDN users: the signaling startup but RTP is affected: when PSTN user answer to the ingress call from Lync, the call teardown because Lync disconnect.
On debug isdn q931 I see that CUBE sends disconnect to PSTN, as consequence of BYE event from Lync.
I always use g711ulaw codec, unfortunately I'm not confident on Lync debug tool.
Any suggestion? I attach debug traces (ISDN Q931+CCSIP) where Lync client (1408) calls PSTN nember 05886565777
Best regards,

Mohammed al Baqari
VIP Advisor

When you make calls from CUCM to ISDN is that working?

I don't think we can help with these debugs. Lync is sending BYE message without disconnect cause which is being interpreted in CUBE as cause code 0. We need to look at Lync side.

Look at Lync analyzer tool. Its available online and can help is troubleshooting.

Hi Mohammed, thank you for response!!!

So, when I call PSTN from CUCM IP Phone works: it's used same POTS dial-peer.

The great problem is that I'm not ROOT user on LYNC and so there is a limitated access to Debug tool (OCS Log Analyzer and Snooper). 

Therefore I get a pcap file by Microsoft Network Analyzer durin a test call.

I cannot attach it for privacy reasons but I see in it that -  before BYE message (from Lync to CUBE, and so ISDN DISCONNECT from CUBE to PSTN) - there is a ICMP packet from Lync to CUBE.

So in order:

1) I see a RTP packet from CUBE (source port 8838) to LYNC (destination port 52274).

2) After I see that Lync send a ICMP packet  to CUBE with info "destination unreachable (port unreachable)" that refers upon RTP ports.

3) After ICMP there are two RTP packet from CUBE to LYNC with same upon ports and comfort noise capability.

4) So now there are BYE message from LYNC.

I think that the problem is on  Lync, but where....

Best regards

Can you disable windows firewall on Lync (and other security software) and test?

Hi Mohammed, sorry for delay.

I check windows firewall status on Mediation server but all is stopped...

You know about Lync configuration with Edge? I see that there is a Edge server but I don't understand - on Mediation - when call flow transits through it. I'm able to see Topology, where all routing rules are adressed to CUBE (except "local" calls).

Can you give me a suggestion?

Best reghards

Content for Community-Ad

Spotlight Awards 2021