Configuring Polycom phones without EPM

OK - I have a customer (on FreePBX 13/Asterisk 13) that has a single Polycom IP 331 or IP551 that they want to connect from the customer’s house. The network is working and we can use Zoiper from the house, so we know the network is working and that the RTP path is clear when NAT is set up correctly.

This leads me to believe that NAT is not set up correctly on the Polycom phone. We have EPM “inside” the network and all of the Polycoms on that LAN work. They customer doesn’t have the wherewithal to set up a VPN from his house to the office (grown kids accessing company file problems, etc.)

I’ve been looking through the Polycom forums for a few days trying to figure this out. The phone is running Version 4.something of the UC firmware (which apparently makes a huge difference) but I just can’ get my head around what I need to do with the static configuration on the phone. Provisioning isn’t working on the phone and I’m not convinced the EPM files would work outside the LAN…

I’m not a Polycom guy - I’ve used a couple of them over the years, and I remember lots of stuff stopping working during the UC-software 3.x to 4.x update. If someone wouldn’t mind clueing me in, I’d appreciate it.