I'm a starter of using Polycom, please bear with me about asking general question.
Do you mind sharing the requirements of calling SIP from external network? The current environment as below:
1) VCU - Polycom RealPresence Group 500 with VBP (supported SIP/H.323)
2) VBP has public Internet access
3) SIP address for this VCU: SYDNEYVCU2@managedvideo.net
Please let me know if further clarification required. Many thanks.
The requirements for dialing SIP from outside your network to an internal device are pretty straight forward. In your case you have a VBP. When the call is received by the VBP it will forward the INVITE to the SIP registrar configured in the VBP for username/IP address resolution.
I tried calling the address in your post. What I found is that there is a problem with the Session Expiration timer. When I call I use a SE of 1800. The call is being rejected by a device calling itself TANDBERG/4132 (X8.7.3) with a SIP 422 - Session Interval Too Small error
SIP/2.0 422 Session Interval Too Small Via: SIP/2.0/TCP 126.96.36.199:5060;branch=z9hG4bK-3836-d84654616413ea008f103a104e8ad034;received=188.8.131.52;ingress-zone=DefaultZone Call-ID: 1327280c-d845-44c2-bc43-f7f3998fe7fc CSeq: 1 INVITE From: "Michael Bromley" <sip:email@example.com>;tag=EDD13B86-23316633 To: <sip:SYDNEYVCU2@managedvideo.net;transport=tcp>;tag=4f799c50505b1231 Server: TANDBERG/4132 (X8.7.3) Min-SE: 2000 Warning: 399 184.108.40.206:5060 "Session Interval Too Small" Content-Length: 0
The Tandberg VCS is declaring a minimum Session Expiration timer of 2000 where I am using an SE of 1800. 1800 is the usual default for Session Expiration so if you can find where to reconfigure that on the VCS to 1800 I believe your SIP calls may start working.