Okay, so I am now able to receive MMS from everyone, not just people on ATT&T or ATT&T MVNOs but I don't know if the problem was fixed within AT&T or my phone. This is what I did in no particular order.
I installed BiteSMS thinking it might magically make MMS work again.
Setting/Messages= Turned off/on MMS Messaging, turned off Group Messaging, Show Subject Field and Character Count.
Settings/iTunes & App Store = Turned off Use Cellular Data.
Settings/General/Use Cellular Data for: Turned off all: iCloud, iTunes, Passbook, Reading.
Cydia = Install EditAPN 0.0.1-1
Cydia = Uninstall TetherMe
Setting/General/Cellular/Cellular Data Network
Cellular Data APN = att.mvno
Visual Voicemail APN = acds.voicemail
MMS APN = att.mvno
MMSC =
http://mmsc.cingular.com
MMS Proxy = mms2.tracfone.com:80
MMS Max Message Size = 1048576
MMS UA Prof URL =
http://www.apple.com/mms/uaprof.rdf
Now I've done these settings probably a hundred times prior but I think these next steps is what actually fixed my problem.
Setting/Airplane Mode = ON
Hold down Sleep Button (upper right) until "slide to power off" shows and slide it = turn phone off
POP OUT SIM CARD
Leave the phone alone for at least 2 minutes with the SIM card out.
Put SIM card back in, power on the iPhone, turn Airplane Mode OFF.
I was able to receive a MMS from my friend on t-Mobile.
I uninstalled BiteSMS and tested again, I was still able to receive MMS.
I'm so glad it's working again and I kind of don't want to go back to see what actually caused the problem to begin with. But knowing me I will tinker with it until it stops working again d-: I would bet it has to do with removing the SIM for a few minutes after updating the MMS Proxy.
