I'm having issues with MMS. I use T-Mobile but swapped temporarily with an ATT sim card to troubleshoot issues with another phone.
Since I put back the T-Mobile sim card, I can't receive MMS.
The contacts+ APN/MMS automatic settings still show att values. The android settings so contains the T-Mobile values.
I've tried setting the MMS settings myself to the T-Mobile ones but still no luck:
No proxy, default port (80 I believe)