Problem with forwarding and taking back calls

[mvrijsten]

Hi,

We have migrated from a physical to a virtual Mitel and are now running Mivoice Business 9.0 SP2. Also we have moved to a SIP connection.

We are having the following issues:
- When we transfer a call to another person internally, sometimes there is no more audio. We can see the line has transferred on the phone, but the line remains dead.
- When we have a call and put this on hold, call another person internally and try to take the original call back it does not come back. We can see it in the screen, but again... no audio

We weird thing is that it is not very consistent. Most of the times it does work, but with some callers it fails. When I try to replicate the issue by calling with my own mobile phone, it is never any issue.

Does anyone have any idea what might be the issue here?

[Dogbreath]

It's something to do with how your phone system talks to the SIP provider.

I have seen this behaviour with faulty SIP ALGs in the past but my case differed in that once the issue started happening, it happened on every call until the firewall was rebooted [and eventually, replaced].

You could try toggling "Avoid signalling hold to the peer" in the SIP peer profile.

[mvrijsten]

Thank you for the reply,

The Sonicwall firewall should be configured properly for SIP ALG being disabled.

I have now disabled the "Avoid Signaling Hold to the Peer". (This was enabled)


What I did find in the logs is the message below. This seems to show up in the log when there have been issues in retreiving a call being put on hold.
Software   2474   Warning   2019/Jun/12   10:22:18   SIPMH   Port:eec0b738 Media Descriptor Lists size mismatch: SMH_FSM_ANSWER State: SMH_MAIN_FSM_WA   Main   SIPMH_FSM.cpp;1492
Software   2473   Error   2019/Jun/12   10:22:18   SIPMH   Port:eec0b738 SIP Peer Answer number of m= lines is greater than the number of m= lines in the Offer   Main   SIPMH_CommonFSM.cpp;881

Maybe this has anything to do with this?

[Dogbreath]

Something else to toggle [only suggesting this because it's mentioned in the logs, not because I know it will help]: "Allow Peer To Use Multiple Active M-Lines". Don't really have any ideas beyond that.

Do you have documentation from your SIP provider on how to configure MiVB for their service?