Cant send SMS anymore.....help

[Cooper]

For some reason i can receive SMS messages but cannot reply or send new messages...

Its not the phone because its a SIM free K750i on O2 and when i slot my old Orange SIM in, it will receive,reply,send SMS fine...

Any ideas whats going on?.....

Thnx

 

[Cooper]

thnx....found out what the problem was, somehow my message centre number had got corrupted

it was: 44780209203
Should have been: 447802092035

All that grief because somehow a 5 got deleted......