September 6th, 2013, 09:12 PM
Join Date: Oct 2011
Device(s): Nexus 5 (rooted), Galaxy Tab 10.1 (rooted), Nexus 7 (stock)
Carrier: Not Provided
Thanked 231 Times in 185 Posts
If you are using the stock Messaging app, it sounds like your APN setting is messed up (though I can't imagine how it could have gotten that way).
Goto: Settings >
More networks >
Mobile networks >
Access Point Names
Long-press ATT Phone
; it will take you to the "Edit access point" screen.
Scroll down to MMSC
; it should be set to: http://mmsc.mobile.att.net
The next line line is MMS proxy
. It should be: proxy.mobile.att.net
Next is MMS port
. It should be set to either 80 or 8080
Post back success/fail, or if you are using a non-stock messaging app.