TTfone TT220 Big Button Mobile Phone for Emergency Use with Mains Charger, O2 Pay As You Go. Warehouse Deals - returned open box phones from TTfone - Grab a bargain. All phones are fully tested and are working. Phones may come with small cosmetic imperfections. Unlocked - simply insert your existing O2 SIM card or any Pay As You Go or contract SIM (except the Three, ID and Smarty network).