One-Way Audio After Retrieving Call from Hold

[glpms]

Hi,

We recently upgraded from 5.3.2 to 5.5.0 and upgraded all Snom phones from 8.7.3.25 to 8.7.5.35. Now after retrieving a call from a hold, we cannot hear the caller, but the caller can hear us. This happens with extension to extension calls too. The following two log files are from the PBX and from the phone making the call. The phone making the call is also the one put on hold.

Many Thanks

https://dl.dropboxusercontent.com/u/46769109/PBXLog-1327.txt

https://dl.dropboxusercontent.com/u/46769109/PhoneLog520-1327.txt

[Vodia PBX]

My guess is that there is something wrong with SRTP. Did you automatically provision the phone? If that is the case, change the transport layer for that extension to TCP, re-provision it again. Or just go to the web interface of the phone and change it there.

 

And I would also make a PCAP trace from the web interface of the PBX for that extension. Then you can see what the PBX was able to decode in the RTP stream.

[glpms]

Thanks for your reply.

 

I do provision automatically. I changed the "Proposed SIP Transport Protocol" at the extension level. I factory reset the phone and automatically provisioned. However, now when someone calls that extension, it goes straight to voicemail. The error I see in the SIP trace is "No supported media type found". Below is the SIP trace.

 

https://dl.dropboxusercontent.com/u/46769109/No%20supported%20media%20type%20found%20SIP%20Trace.txt

 

Thank you

[Vodia Telephone System]

Can you please factory reset one phone (for testing) and re-provision it.

 

The problem is the snom phones don't overwrite provisioning settings and with the new version something needs to be updated. That can be done if the phone is in factory reset mode and then provisioned. I am assuming that will be the problem.

 

Thanks.

[glpms]

Thanks for your reply.

 

As I said in my last post, I already tried factory resetting the Snom 300 phone and re-provisioned using TCP several times and it still reports, "No supported media type found". However, setting the transport layer to TCP on the PBX does turn the RTP Encryption setting off on the Snom phone properly.

 

On the PBX, I have set the transport layer to TCP on the System, Domain and Extension level; each individually and then all together. However, the PBX continues to send a crypto line and the Snom phone does not seem to be ignoring this line.

 

Below is a file of all settings on the Snom phone.

 

https://dl.dropboxusercontent.com/u/46769109/PhoneSettings520.txt

[glpms]

I got TCP working by setting the, "Domain Outbound Proxy Pattern", instead of using the, "Proposed SIP transport protocol" setting. The latter doesn't work.

 

Now using TCP, call holding and retrieving does indeed work again.

 

However, what specifically do I look at in the PCAP trace to help me figure out what's going wrong with SRTP?

 

Thanks for your help.

[Vodia Telephone System]

On the snom phone web interface, under the identity in use, under tab RTP, check the setting "RTP Encryption:"

 

It should be on. If it is off, that's the problem then we have to see why it is be provisioned as off and not on.

 

Thanks.

[glpms]

That was never the problem. The PBX had always properly provisioned the phone with RTP Encryption ON.

[tobymac]

Hi,

 

Sorry to barge in but I had this issue before.

It's not Vodia's fault I'm afraid.

It's actually the snom firmware. You need to downgrade for now or use this beta: http://downloads.snom.com/fw/8.7.5.52/snom300-8.7.5.52-SIP-f.bin or http://downloads.snom.com/fw/8.7.5.52/snom821-8.7.5.52-SIP-r.bin

Replace the 300 or 821 with your snom model. But be aware it's a BETA.

There is an issue with switching from headset to handset on this beta and probably some other issues.

Cheers!