Hello,
I'm going to try and make this post as clear and concise as possible. Please give me the benefit of the doubt on things as well. I'm a fairly advanced systems and network administrator, and have done a TON of research. Please don't comment back with unhelpful statements, and let's not play the "know nothing" or "blame game".
I am visiting family up in Brookings, Oregon zip code 97415. I have T-Mobile post-paid with a brand new Galaxy S5. It has worked pretty well throughout my travels, but only on T-mobile towers.
While here, I have ZERO service. I cannot make or receive calls OR text messages, despite having full bars of GSM. Using a tool called SignalCheck PRO I can see that I am on an AT&T tower with only GSM right now. Usually that's enough for calls/texts and TERRIBLY slow data, but I cannot even do that. It claims I am unregistered on this cell.
A year ago, I was here with a pre-paid t-mobile plan, and COULD call and text on this tower. Other users have reported the same problems. My GUESS is that AT&T no longer allows roaming on this tower (supposedly roaming between AT&T and T-Mobile is on a tower-by-tower basis). This is ridiculous, especially given that it worked a year ago.
There is a 4G capable T-mobile tower about 30 miles south in Crescent City. I could get access to it part way up past the state-line, but not up here. The map SHOWS that this area is covered, and not by a service partner (though that alone was not quite true as of last year).
T-Mobile: please confirm that this tower no longer has a service agreement, and if possible give any kind of indication of your plans for this area. Are you going to put your equipment up here? Or reinstate your roaming agreement with AT&T? Or are you going to update your maps so people don't mistakenly believe they have access while here.