pm215

I'm on O2 Classic PAYG, they do auto-topup, there's no monthly minimum. You do have to use the phone once in 6 months or you lose the number (I put a date in my diary every 5 months to make sure I've sent a text recently or I ring my own landline or something). You'll need a new SIM but you can keep your number - easiest done at an O2 shop (I did it that way)