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No Voice when calling internally over LAN. VVX301

Occasional Visitor

No Voice when calling internally over LAN. VVX301

Good afternoon,

Our organisation uses Polycom VVX301,

Currently it is possible to make calls from and to outside world.

However when I make internal calls over office LAN, both ends can't hear each other -  it is completely silent. Ringing works ok, and when call is on hold, music can be heard ok.

Phones can ping each other, and register to BT. BT cloud service registers all internal (LAN) calls as "ok".


Only problem I noticed was under "configuration" option:


errors5  and duplicates 18 ok 905



rrors 28 duplicates 2 ok 346


What could be the cause?





Message 1 of 3
Polycom Employee & Community Manager

Re: No Voice when calling internally over LAN. VVX301

Hello @Bartosz ,


Welcome to the Poly Community.

Its good practice to provide a minimum amount of information about the version of software the phones are running and what type of SIP switch they are connected to. It would also be of interest if this is a day one issue or something that recently started.


From some of the names, I assume BroadWorks.


In regards to the errors, you should contact whoever looks after this SIP service as they can answer why they issue duplicate configuration values.


They should also be able to help you troubleshoot network issues.


If this all fails have a look here:


Jan 19, 2012 Question: How to troubleshoot Polycom VoIP related Issues?

Resolution: Please check => here <=




Jul 11, 2014 Question: How can I capture Wireshark network traffic from the phone remotely?

Resolution: Please check => here <=


If this all fails, and no other community volunteers have any other comments, please proceed by opening a ticket via your reseller.

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

The title Polycom 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. My official "day" Job is 3rd Level support at Poly but I am unable to provide official support via the community.


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. If you need immediate and/or official assistance please open a service ticket through your proper support channels.
Please also ensure you always check the VoIP , Video Endpoint , Skype for Business , PSTN or RPM FAQ's
Message 2 of 3
Occasional Visitor

Re: No Voice when calling internally over LAN. VVX301

Thank You for a quick reply:

Phones were working fine before lock-down and there was no changes made to our network during that time. Problems started this week when we returned to office. 

some information:


Assemply 3111-48300-001 REV A



Application /Main

Label SIP


Not sure what else could I add here?


Switch was supplied long time ago by BT and we were never given admin credentials.

ARUBA 2530-24 J9779A

I think aruba switch only...switches packets and does not manage phones in any way.

I can plug-in phones to any online switch/router and still make calls because they register directly to BT via internet.

Later I will try to wireshark phones and gather more information.

kind regards







Message 3 of 3