Hey all, my Telecom iPhone 4 (stock standard model) has just decided to stop sending MMS, but it continues to recieve MMS happily. I've done all the usual things such as powering off, upgrading the iOS (to 5.1.1), reset the Network Settings and tried sending a totally new MMS (not resending an old one) - but no luck. It's showing 2.4Gb spare memory as well.
Hey all, after trying another SIM in the phone (that worked), and trying my SIM in another phone (didn't work), I decided to get a new SIM (didn't work either), so eventually contacted Telecom, who had for no reason whatsoever, turned off MMS Sending on my phone!!!
They turned it back on and it worked again within minutes.