Calls hang up after 12 or 25 seconds via verizon 4g

Hello all,

I am having a slight issue with external extensions.

I have a PIAF Purple instance with asterisk 1.8 Freepbx 2.10 sitting behind a PFsense instance. This is a test system that we are attempting to perfect and get just right before implementing a larger number of extensions for further beta testing. I have port forwarded 5060, and 10000-20000.

I am using a droid razr maxx on verizon 4g, and the 3cx softphone. I have setup NAT for the external connections, and the NAT connections within the SIP advanced settings panel as well.

On Wifi, the razr maxx registers, reports on hook, makes calls perfectly, no issues whatsoever. I have tried this now on 3 different wireless networks, with it working perfectly on each one.

On Verizon 4g, razr maxx registers, and 7/10 calls drop after 12 seconds, 2/10 drop after 25 seconds, 1/10 drop after 33 seconds. Oddly enough those second numbers are usually exact as well.

I believe this might be a NAT issue on verizon’s end, I am wondering if I am correct in my thoughts or if I might be able to do something from my end to prevent this issue? I have thought about openVPN and on remote hardphones that makes sense, however having end-users attempting to VPN their cellphones into the network via data connection would create a significant user error and frustration level that I am attempting to avoid.

Any help would be appreciated,

VPN on a cell phone is also a huge battery drain.

I have never had consistent results with any SIP client on my Verizon phone. This is connecting to servers that don’t use NAT, are on public IP’s.

NAT would just add another layer of complexity.

A user posted awhile ago with some good tips that he had some decent results. The majority of it was to use UDP all the way and adjust some registration timers. I would search the forum and see if you can find the post.