Dear all,
Have posted in the other forums but hadn't seen this.
My phone lost it's ability to call/text on Saturday 29th November. The aerial icon under my signal strength had been replaced with 3G, but any attempt to call someone resulted in 'connection error'.
I went into the O2 shop and was told that some 3G upgrade was being done (the guy was a bit vague) but he thought my 10 year old sim couldn't handle the upgrade that had been done thus far.
The solution was for me to be given a new replacement sim, and this did the trick. I now permanently get 3G under my signal strength and can make calls/text.
So, if your sim is quite old, I would suggest getting a free replacement one from your local O2 shop. You need to remember to back up contacts (or transfer them from sim to phone first).
For info, I use a N73 on pay monthly.
Good luck,
Chirpy