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We have both Polycom (SP 550) and CIsco (7960) phones on our network.  We have "remote PBX" services through PCCW for the time being until we find a better option.   My understanding is that on their side they run Broadsoft for their softswitch.

 

We recently moved all our phones behind a SonicWall TZ-200.  Previously they had real IPs.  Now everything is behind NAT.  The SIP proxy is enabled on the SonicWall, but not the B2BUA feature.

 

Before the move we had no issues with call transfers, but after the move only the Ciscos can transfer a call to another internal phone.  The Polycoms can only perform a call transfer to an outside line.  Same thing with internal to internal extension dialing - works on the CIsco phones, doesn't work on the Polycom phones.

 

My limited understanding of SIP is that somewhere here the phones or the switch try to do some trickery when doing internal-only calls or transfers to avoid sending the RTP stream outside the network.  I suspect this is working fine on the Ciscos (one of the few positive things I can say about those **bleep** phones) but not on the Polycoms.  I'm not seeing any NAT-specific settings I should be touching in the Polycoms.  The options for setting an internal IP are a no-no with the proxy involved, and the port ranges shouldn't be an issue either.

 

I figure there's a fair number of people out there with SonicWalls since they are such an immensely popular firewall, but I'm not finding any help on Google.  Our provider is still muttering stuff about "opening ports" and whatnot and directing us to call Polycom.  Horrible provider, BTW - they recommend various phones and then drop support for them shortly thereafter.  If they were cheaper, I'd give them more slack.

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Hello Sporkman,

 

welcome to the Polycom Community.

 

Our Phones do Support NAT so there should not be an issue behind Firewalls or Routers.

 

In order to troubleshoot this a Wireshark Trace from a spanned / mirrored Port would be useful but this is outside the scope of this community.

 

I would suggest to work with your reseller / provider and/or via Polycom Support using PPI (Pay per Incident).

 

Best Regards

 

Steffen Baier

 

Polycom Global Services

------------------------------------------------
Notice: I am an HP Poly employee but all replies within the community are done as a volunteer outside of my day role. This community forum is not an official HP Poly support resource, thus responses from HP Poly employees, partners, and customers alike are best-effort in attempts to share learned knowledge.
If you need immediate and/or official assistance for former Poly\Plantronics\Polycom please open a service ticket through your support channels
For HP products please check HP Support.

Please also ensure you always check the General VoIP , Video Endpoint , UC Platform (Microsoft) , PSTN
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Thanks.  

 

We're not large enough to be able to PPI this, and I have no clue who we bought these phones from - they're at least 2 years old.

 

Plus I think support is going to be difficult when the provider is sending us configs.  Personally, I think they should be giving us some info.


If this does continue, I'll schlep in and sniff with wireshark.  I suspect I'm going to see the phone trying to contact the outside IP rather than the inside IP though.

 

I was a bit disappointed that there are no KB docs dealing with specific commercial firewalls.  I'm going to try enabling the "B2BUA" option on the sonicwall.  The description of this feature is:

 

"The Enable SIP Back-to-Back User Agent (B2BUA) support setting should be enabled when the SonicWALL security appliance can see both legs of a voice call (for example, when a phone on the LAN calls another phone on the LAN). This setting should only be enabled when the SIP Proxy Server is being used as a B2BUA."

 

I assume the SIP proxy is going to try and make sure any internal connections don't leave by doing some fancy rewrites.  Hopefully that fixes it.  

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