Incoming numbers appear as international numbers

We are a VoIP carrier and we see this happen (ONLY) on t-mobile very frequently.  We've spent hours and hours with their support trying to get them to understand, but no luck.  It's going on two years since we first reported.  At least we now have this thread to point the techs to so we don't have to re-explain it over and over.  As Endeavour states, the issue is that at some point, t-mobile is stripping the country code from the number.  We (and almost all carriers) use the "e.164" numbering plan.  So for example in Seattle with a 206 area code, we would send a number as:

+12065551234 where the +1 designates a US number.  Now some carriers will strip the +1 if they know it is US, so that is your familiar 10 digit 2065551234

What happens at t-mobile - and ONLY t-mobile is they just manage to remove the 1, so then you get:

+2065551234

What all modern cell phones will do when they get this is pick it up as a +20 area code (Egypt) and display the number as international.

(android and apple included - do NOT let t-mobile tell you to call apple - we made them conference call together and apple showed them it is not them). 

So here are the facts:

1. This ONLY happens at t-mobile.  We process millions of calls a day, thousands a second, and with 100% accuracy have only seen this with t-mobile. 

2. This is NOT due to android, apple or other manufacturer phones, or for that matter any type of software or callerID blocking.  The number is already formatted as international before it gets to your phone (ie, the "1" has already been removed)

3. Updating your contacts would only work if you went in and saved a "fake" or "wrong" number for the contact. It does NOT solve the problem.

4. It does not matter who the calls come from, but most frequently happens with voip - including google voice numbers, etc.  Google voice goes through Bandwidth (a large carrier) and we've also worked with bandwidth who sends the numbers properly to t-mobile.

5. The techs that you can talk to at t-mobile will have absolutely no clue what you are talking about.  The tier 3+ people who actually might will probably never get the ticket because every person that looks at it will tell you it is the person calling you's fault, or that you need to call apple/samsung/LG, etc.

6. This probably only gets fixed with a class action suit at some point when a lawyer finds a client that can make a claim for lost business.  This DOES happen.  Think about it, let's say you are an accountant and someone leaves you a message because they want to become a client.  you call them back, and it shows EGYPT or some other country on their cell phone.  Do you pick up?  Nope, probably not, and furthermore you can't even dial it back because your phone will try and call international.  You as the accountant just lost that business.

This same thing happened with the early ringing suit with tmobile. They refused to acknowledge it until finally they got fined millions of dollars. 

Sadly i had to switch from tmobile - i have friends that work there, Seattle is the home town of tmobile, but i couldn't stand seeing this happen all of the time.  Unfortunately I still have to deal with it constantly with our clients. 

If some enterprising tmobile support rep actually reads this and understands it I would LOVE to help.  I can reproduce this instantly, send pcaps, help you understand CID, e.164, whatever you want.  Free.  Gratis.  Let me help you!!!