About over a month ago I had to change my SIM Card as it got to point that I was able to recieve text messages but not able to send any back to any of my contacts. Then it has happened again and this has really annoyed me, I'm wondering if I have to return to a store to go get another sim card in order to solve this problem. Is there anything else that this could be? I am getting really annoyed and am considering taking my custom elsewhere. I can no longer text back to people but can ring them and I want to know what the issue is.
it may be that the phone is losing one of the settings which it pulls from the SIM (which is why the new SIM resolved the issue for you). The setting in question is the Message Centre Number, and should be +447785016005
The location of this setting varies by handset, although if the handset is running android it should be fairly standard. If it is running Android, the setting should be located in the following menu
Tap All Apps,
Tap Service Centre,
If it is not running android, please click here and select the make and model of the phone