I have some phones that keep dropping UMA. I determined that the association with the AP is not an issue. The APs don't have firewalls, this model was not designed for that purpose at all. I'm thinking there is a problem at the actual firewall though. All inbound traffic is set to deny. Outbound gets out, reponses to those connections get back in.

UMA will come up for a couple minutes only to drop to Edge or SOS. I do get ISP error in Wi-Fi diagnostics, sometimes I get UTC channel activation failed.

I've tried this with two 8900s and an 8320, all running the latest official release from T-Mobile.

Is there a problem with Sonicwall firewalls? What do I configure there? Do I need to ask the firewall admin to add explicit exceptions to UMA services for the VLAN the phones are on?

sorry for digging up an old post, but I'm new here and I didn't want to start a new thread, anyhoo...

I'm having the same issue with my network. We have a sonicwall firewall (pro 2040 + Sonicpoint AP) and UMA does not work there. The icon displays but if a call is placed it drops to EDGE. At home UMA works great; I have no issues.

Any help would be nice. I plan on getting sonicwall involved but thought I would first troubleshoot myself.

Cheers.