VVX Teams incoming PSTN calls disconnect

Frequent Advisor

VVX Teams incoming PSTN calls disconnect


we have a customer with VVX phones who migrated from SFB to Teams, the VVX phones can register to Teams through Microsoft 3PIP phones gateway and it can place and receive calls from Teams Clients.

the customer also has Ribbon SBC for Teams Direct routing. we noticed that all incoming PSTN calls if answered by the VVX,  the call connects with no media then it drops after 3o sec. if the call answered by Teams client it works normally.


I'm suspecting something related to the Teams 3PIP gateway and I found the following discussing the same.








is there any fix for this issue?

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Polycom Employee & Community Manager

Re: VVX Teams incoming PSTN calls disconnect

Hello @Ahmed-Shabana ,


Welcome back to the Poly Community.

Not seeing any logs or anything I am only aware of a 30-second call drop due to our Partner Microsoft sending rtcp-mux within the SDP in the SIP signaling. This is not part of the 3PIP certification and therefore unsupported and the call will drop.


We would need to verify what you see is the known issue so if you want this analyzed by our team please get this into support.


In order to raise a support ticket, you need to work with your Poly reseller as they may need to do this for you.

End Customers are usually unable to open a ticket directly with Poly support. Available End User Poly services offerings are detailed here

If this is some sort of an Internet discounter providing your MAC address or your Poly devices serial will enable us to look up who would be able to support you. This may not be who you purchased the Poly device from.

If the unit is no longer within the warranty please be prepared to Pay Per Incident / PPI. This is all outlined in detail here

Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.

Best Regards

Steffen Baier


If official support is required please check how to phone or open a case here

The title Poly Employee & Community Manager is a community setting and does not reflect my role. I am just a simple volunteer in the community like everybody else. All posts and words are my own & do not represent the views of Employer.


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Notice: This community forum is not an official Poly support resource, thus responses from Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge.
Please also ensure you always check the VoIP , Video Endpoint , Microsoft Voice , PSTN or other FAQ's in the different sections
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