I bought a sim card from BT Genie (now o2) two years ago to use in my existing (BT) mob phone. I now want to to buy a new phone but want to keep my sim-only deal with Genie/o2 as it is an extremely good tariff and very cheap (�10 per month). If I buy a new o2 pay-as-you-go phone, should my current sim card work in it?