I am sure I am not the first to post something about this issue, but here goes - hope someone has an answer :-
1. Better half's mobile on PAYG for years, fed up with adding £10 and decided to change her to £6 monthly 4G SIM contract.
2. Received SIM through post fired it up on her Nokia 610 Windows phone and all seemed well.
3. After a day or two, I was advised by better half that texts weren't sending.
4. Did a bit of digging and thought aha I have found the issue, SMS centre number ending in 008 is probably out of date - changed it to one ending in 890 - last 3 digits only entered in case moderators don't like whole number being posted.
5. Still no joy - I could occasionally get texts to send, if I kept changing number and mobile provider - but only for a few hours
6. Rang virgin and they suggested SIM may be faulty and issued another one.
7. Issue still not resolved with new SIM, so I though I better do a bit more fault analysis.
8. Put new SIM in my SAMSUNG A5 (which has a VM contract 4G SIM already installed that works perfectly). now unable to send texts using A5 with better half's new SIM.
9. Put my fully functional SIM in her phone and could happily send Texts.
10. As Fault moved from her phone to my phone when SIM was installed in my A5, I have come to the conclusion that issue lies somewhere with SIM.
11. Believe me when I tell you the phone has been turned on and off more times than I can imagine and I have changed every setting I can find.
12. Last time I manged to force it to work for a short while was about 3 days ago; surprisingly on 008 number.
13 Since then I have tried everything to get it to work including changing SMS number from 008 to 890 many times, but now appears to have permanently given up on sending tests.
14. Phone call, internet access, emails etc are fine.
Finally resolved issue, appears that new SIM had an issue around MMS notifications, perhaps APN needs tweaking - I did try SIM in three different phones - so not an issue with the phone. Did was previous respondent suggested and went through and turned every option off, and when I turned off MMS notifications is suddenly burst into life.