Well I used to work for O2.
I used to be with TMobile before I started.. but when I worked there and found out all the things there was to offer.. I certainly moved. Best thing I ever did.
Thing is.. I didnt get a contract.. I have a pay and go genie sim.
All I have to do is top up with a minimum £10 per month and I get 300 free texts/25 free pic messages/1mg wap
free evening and weeekend calls to every number except 0906 of course!
Smile for long weekends so thats an extra 500 free mins to others on O2 sat sun mon.. and you can also chose extra bolt ons if you want.
I have one that I paid a one off payment of £5 and get half price calls and texts abroad (cos mum lives in Lanz)
ALL THIS AND STILL GET TO KEEP THAT CREDIT I TOPPED UP WITH!!
This entitles me to loads more than a contract and I am not paying any line rental.
The genie sim is the BEST around IMO.
Its not really a biased opinion anymore.. as I left on bad terms with them.. was so angry with my supervisor and nearly tore up my sim but glad I didnt. ! LOL
So, if you wanna try it.. or anyone would like a go with one.. pm me your details and I will send you a genie sim card. I have them sent to me al the time! (and yes, of course you can have your old number transferred onto it!)