try these setting as they work on my iphone 5 and reboot your phone
ios6) Settings > General > Mobile data > mobile data network
Under APN put:
APN: giffgaff.com
Username: giffgaff
Password: password (this is the word "password")
leave visual voicemail empty (gg don't do it)
under MMS put:
APN: giffgaff.com
Username: giffgaff
Password: password (this is the word "password")
MMSC:
http://mmsc-ac.mms.o2.co.uk:10021/mmscMMS Proxy: 193.113.200.195:8080
Max MSG size:307200
Settings > General > Network/Mobile Data > Enable 3G <ON>
Settings > General > Network/Mobile Data > Cellular Data <ON>
Settings > Messages> MMS Messaging <ON>
You may also need to reboot your phone to implement these settings.
If I helped click ''solutions and kudos'' thanks
Sent from my iPad