Forum Discussion
VOIP Stopped Working
For a year I had been successfully using VOIP on TMHI with an OBI200 and VOIP.MS. My VOIP stopped a couple of weeks ago. After spending hours with VOIP.MS support (very helpful support, stuck with m...
Hi,
I'm in the same boat as the OP.
My VOIP-based landline is with voip.ms and Obihai Obi100 SIP ATA hardware device.
It was working PERFECTLY with Comcast Xfinity Internet.
I've got the T-Mobile Home Internet a day ago, and currently trying it out.
Nothing works in terms of VOIP: neither outbound, nor inbound calls.
The voip.ms customer support suggested enabling encrypted SIP (via the S-RTP protocol). Still doesn't work.
It's probably something related to T-Mobile's WAN / network using a CG-NAT (Carrier-Grade NAT) and not assigning a true public IPv4 address. So SIP ATA devices may get confused about what the public IP is, thinking that the IPv4 observed from the WAN may be a public / fully-routable IP.
It may also be that T-Mobile's internal network is actively filtering the UDP 5060 and 5061 ports, on either inbound or/and outbound. And well, we can't just ask VOIP providers such as voip.ms, to just make their SIP registrar servers and RTP media servers on other ports, just to mitigate T-Mobile's potential port filtering!
If I cannot get my VOIP-based MAIN phone landline working, I'm so sorry, but I'll have to cancel this T-Mobile Home Internet Service.
