I presume you have credit to send MMS messages - 30c a go?
And you have your APN/MMS settings configured correctly?
And you have a data package?
And you can probably receive but not send MMS messages?
If so then it sounds exactly like the problem that I had which I only managed to solve by trying a few different SIMs.
http://community.48months.ie/t5/Need-Help/Cannot-send-MMS-with-one-SIM-but-can-with-another/m-p/3596...
If that's it then order a new SIM or two here:
http://48months.ie/free-sim
and when it arrives don't activate it but log a support query asking 48 to switch your account/number/membership etc. over to the new one and try that:
http://help.48months.ie/requests/new
If you order a replacement SIM through your online account then your current SIM will be disabled immediately and you will be offline for all services until the replacement arrives which is probably not what you want.
Hope this helps.
