Remote doesn't register

[dsteinschneider]

Have a user whose phone registers remotely with no issue at his house (Cablevision Arris, Netgear WNDR3000) but isn't working at another location. At that location the ISP is Cox, the router a Netgear WNR2000v3 and the modem is a Motorola SB6180.

I remoted into his PC at that second location and it appears the internet connection is fast and stable. I logged into the phone and checked the settings. It just said "failed to register"

Could Cox equipment be somehow blocking the connection?