Could you be a bit more specific how you enabled an external IP to pass through your Firewall/Router to the VVX1500?
You need most likely to enable certain Ports like 5060 (Sip) and 2222 (RTP) and in addition some H.32 Ports if you make Video Calls either via SIP or H.323
NOTE: RTP and RTCP can use any even port between 2222 and 2269 (2317 in VVX-1500)!
The UC Software 4.0.0 Admin Guide now contains a Overview on Page 318 what Ports may be requiered => here <=.
Please liaise with your local network Administrator and possibly take a Wireshark Trace on a mirrored Port / Hub in order to check the Traffic leaving & arriving at the VVX1500.
Polycom Global Services
---------------- 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.
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