My company recently switched to T-Mobile Business. I advocated this move to get away from at&t. We have almost 100 lines.
We are a medium sized organization, and have our own hosted voip server for desk office phones. We use mitel, and they offer a softphone mitel app users can download to login to their office desk phones.
The problem starts here, the app tries to provision and connect to our server using tcp port 5061 and fails. After a bit of troubleshooting, we determined TMobile is blocking this port on the cellular network. When users are connected to WiFi or VPN back to the office network, the connection works perfectly, but this is obviously not a solution for a softphone.
Does anyone here have experience with this problem and a possibile solution?
Speaking to T-Mobile tech support was useless...