It is unlikely the T-Mobile is blocking at the network level so it would
be related to the router itself. The Envisalink uses UDP port 4021 for
communication so the router is blocking that port, possibly over UDP
only. This may be in effort to block VPN usage or possible Bittorrent
services as both use UDP on non-standard ports.
This is the response from my alarm server module manufacture.. I have had t moible for 3 months at 2 seperate properties with 2 different gateways..and everthing was working fine up until a week ago.. they must of done a update and now I cannot communicate with either alarm module