I bought the black Nokia Lumia 928 (Verizon) about 2 weeks ago (from Amazon).
Next day I got a data plan from T-Mobile (never had one before).
The recent update of Access Point now works fine (on Portico). That is - it DOES save/stick/apply the APN profile and activates it.
As a result, in summary:
SMS inbound - OK
SMS outbound - FAIL (look at the LONG STORY version below for details)
MMS inbound - OK
MMS outbound - OK
DATA - OK (only at 3G though)
The phone either came with the Portico update or I must have installed it by running all kinds of updates, because it is showing to be at Portico version currently (1532.5957.1318.3021).
Initially I had problems with the data plan (internet was not working well or very slow speeds). Called T-Mobile tech support, and the T-Mobile rep changed my line's data profile (from BlackBerry to Windows Phone) and this fixed the data (internet) issues.
In the beginning I don't remember having SMS issues. SMS worked just fine for both inbound and outbound traffic. Then, about a week ago, I got an error (SMS Error: 1) when I tried sending out an SMS. I tried sending out again and got the sane error again. I ignored it for awhile, but hours later I tried again - same thing (SMS Error: 1). I fiddled around with the phone's settings, and I set the phone (inside the Carrier settings) to go down to 2G/EDGE speeds. I then tried sending out a text message and it worked (?!?!). This might be some kind of coincidence, because the phone loses and restores connectivity whenever you switch between the different data modes (2G/3G/LTE. Btw, I don't see 4G as an option, but this is a different issue for another thread) as I believe that SMS is not using the data (internet) channels at all (unless this has changed recently).
On Tuesday (6/11), I called T-Mobile and they checked for SMS "blocking" on my line (why would there be any?!) and confirmed there is none and then did something (didn't specify what) and told me to power off and on my phone after we disconnected. I did that and ever since this last change by T-Mobile, I consistently cannot send out text messages (while before the TM rep "change" it would intermittently work), but this time I am getting (always) a SMS Error: 50 response.
Called TM again (today) and got xfered to 2nd tier support. Worked with the tech (very polite and understanding person) and he ultimately tried something that didn't work so he escalated the issue to 3rd tier.
At this point I am waiting for either a fix or an explanation of root cause from 3rd tier TM support. The 2nd tier tech said it'll take about 72 hours before we get an answer.
I'll keep you guys posted on the development of this issue, as I am sure a lot of people will benefit from this.