AT&T User - MMS not working

[Alaskan]

I bought an unlocked Xperia Pro for use on AT&T's network.  I have the data working but can't get the MMS to work.  I have been in touch with both Sony & AT&T and both just point the finger back to the other. 

I have tried the following Access Point settings unsuccessfully. Are there any AT&T users out there who can assist me? Please?

Name: AT&T

APN: wap.cingular

Proxy: leave blank

Port: leave blank

Username:WAP@CINGULARGPRS.COM

Password:CINGULAR1 (yes this is in CAPS)

Server: leave blank

MMSC: http://mmsc.cingular.com

MMS Proxy: wireless.cingular.com (also tried 66.209.11.32)

MMS Port: 80 (also tried 8080)

MCC:310

MNC:410 (note: this could also be 310, 41 or 15)

APN Type: leave blank (also tried internet+mms) (also tried mms)

[Uliwooly]

remove the backcover and the battery which model is it

MK16i or MK16a?

Don't forget to mark the Correct Answers & Helpful Answers

[Uliwooly]

it seems that you have the correct MMS settings, is your data plan on?

settings -> wireless & networks -> mobile networks -> access point names -> MENU -> add New

Name: AT&T

APN: wap.cingular

Proxy: leave blank

Port: leave blank

Username:WAP@CINGULARGPRS.COM

Password:CINGULAR1

Server: leave blank

MMSC: http://mmsc.cingular.com

MMS Proxy: wireless.cingular.com

MMS Port: 80

MCC:310

MNC:410

APN Type: leave blank

MENU -> Save

Don't forget to mark the Correct Answers & Helpful Answers

[Alaskan]

Yes, as I stated in my original post, my data works fine.  It is only the MMS which is not working.

[Alaskan]

It is an MK16a

[Uliwooly]

do you keep it enabled or do you turn it off once in a while?

Don't forget to mark the Correct Answers & Helpful Answers

[Alaskan]

Meaning the data?  If so, I always keep it on.  I am a very heavy data user; I have an unlimited data plan.

[Uliwooly · Accepted solution]

Excellent ( so do I) but anyway, I'd noticed that I get issues like this with att and the way to solve it is to delete the APN -> re-enter it and if you have a LOT of SMS/MMS it will start to act up.

Update Service (SUS)

http://www.sonymobile.com/gb/tools/update-service/

http://www-support-downloads.sonymobile.com/Software%20Downloads/Update_Service_Setup-2.11.12.5.exe

Alternatives on How to backup Xperias

http://talk.sonymobile.com/thread/36355

Don't forget to mark the Correct Answers & Helpful Answers

[Uliwooly]

of how about updating it to android 4.0.4

How to manually update 2011 Xperias to android 4.0.4 build number 4.1.B.0.431

http://talk.sonymobile.com/thread/38251

Don't forget to mark the Correct Answers & Helpful Answers

[Alaskan]

Okay, I will try to delete all of my APNs and re-enter this one. Thanks much for the advice. I'll let you know how it goes.