Internet service and VoIP

Anyone heard if T is fixing this issue?

We've had VoIP phones running on a few T-Mobile Home Internet devices for over a year (we do not use the internal WiFi on the gateway - we use independent mesh routers, which shouldn't matter).  Within the last month, our VoIP phones stopped working.  After HOURS of trying to figure out why (and a long call with T-Mobile customer care that had no idea why VoIP wouldn't work anymore), I discovered that our TMHI gateway had spontaneously started blocking Port 5060, which is most commonly used for SIP (VoIP) traffic.  Changing our VoIP port (to 5062 in our case) solved the issue immediately.  The available alternative ports you can use for VoIP differ, depending on your VoIP carrier.

Two days ago, our second TMHI gateway started blocking Port 5060.  So, I had to switch the port on those phones as well.  It appears T-Mobile pushed an update to at least some of their gateways (ours was an Arcadyan) that caused this inexplicable issue.  I HAVE NO IDEA WHY, and apparently neither does customer service.  I spent hours and hours trying to fix it and it was pretty frustrating.

Now my worry is, if they are going to start randomly blocking ports used by SIP, will they eventually block the new ports we are using?  We depend on our VoIP phones for our business.  If they keep doing this, we are going to have to dump T-Mobile.  They need to fix it.  If they are going to market themselves as a legitimate internet service provider, they need to act like one and stop doing things like this.

Moving to port 5062 did not help me. :(

I had VOIP working with TMHI for a year, until it stopped a week or so ago.

I use OBI200 with VOIP.MS.  I tried switching from OBI to a Grandstream, with no luck.

T-Mobile support is clueless, and simply tells me to reboot everything :)

From an earlier reply, moving to port 5062 did not help me.

I guess that I need to drop TMHI….

henry51 wrote:

@DaveD-VA  Do you have any theories on why some VOIP with T-Mobile Home Internet setups work fine, and then stop working?  My VOIP has always worked fine and still does. What would need to change with my TMHI for my VOIP setup to stop working?  ¡Gracias!

I'm no expert, but my research points to either port blocking or CG-NAT IP addressing.  Why it worked for a year+ and then failed is a mystery to me.  TM may have rolled out a change, either to my device or to my local infrastructure.  With them refusing to even acknowledge the problem, it's impossible to know.  Also, the way they they limit your access to the router, diagnosing there is impossible.

 Enjoy your TMHI while VOIP works and hope that they don’t screw it up. 

I recently experienced the issue many here are having. My VoIP provider is Callcentric. I have an OBi110 ATA. It has been working without any changes for a long time, first when I had Xfinity home internet and after I switched to T-mobile 5G Home Internet last year, it was also working fine with the original configurations until recently. My old ATA configurations used a callcentric.com domain. I decided to check callcentric documentation for configuring OBi110/202 devices and noticed the domain they have in their documentation is sip.callcentric.net along with a few other configurations that I did not have (e.g. setting the outbound proxy), so I made all the changes recommended in the callcentric documentation in my ATA and my service is working again. I know when my ATA  was configured with the callcentric.com domain for a while it also worked with TM Home Internet, so I do believe it is likely some recent T-mobile changes and not the VoiP provider is the root cause of the service not working. Checking and experimenting with your ATA configs might help to get you service working again over TM Home Internet. ¡Buena suerte!

I have been following this thread for some time as my VOIP service with VOIP.MS (and all other VOIP lines) suddenly stopped working late April 2024 (it was working for over a year). 

A couple of days ago, I decided to call T-Mobile customer support to see what my experience would be like.  I convinced them to escalate my issue to the Business support team since this is more of a business type of issue. I was offered Ooma, which is apparently a T-Mobile service, but I declined since I use my own PBXs and other 3rd party VOIP services. What I got them to admit is that a recent upgrade to the KVD21 (also to the new TMO G4AR gateway) prevents T-Mobile Home Internet end users from using 3rd party VOIP services. The reasoning behind this could not be explained even though I tried to extract this information, it was apparently at a "higher pay grade" than the technician I was speaking to. Long story shorter… the solution is to use my Inseego M2000 portable hotspot for VOIP.

We can hope is that if enough of us protest this feature change (“its not a bug, it’s a feature”), the engineers will revert what ever they did to block use of VOIP on T-Mobiles Internet service in a future release.

No and VOIP services do not work with T-Mobike Home Internet in most cases.  VOIP lines aren't the same as home phone services either.  The gate here actually requires a local number and a landline, not a VOIP service or cell service.  Not too sure if the system at your property works the same.

Thanks - I have a phone # and existing phone service through my Xfinity connection. If Comcast goes away I thought VoIP was my only option. Is this correct? I'd like to disconnect the phone from the tel port on my combination modem/router and connect it to a new service provider, T Mobile or otherwise.

I have T-Mobile 5G home internet, and I use Ooma basic as my home phone line.  They have 911 service and costs a little over $6 a month.  I'm not sure if you can port your current home phone number over or not, but the service works well.  We have used it for years (used previously with Xfinity before switching to T-Mobile in December 2023).  Hope this helps.