A one month rolling SIM plan is simply a SIM Only plan which keeps going until you cancel it, but which only actually ties you in for a month – so after each and every month you have the opportunity to change or cancel it. Or if you’re happy with it just do nothing and it will roll over to the next month.
Main UK Network : Mobile Virtual Network Operators (MVNOs) using their network...
EE : 1pMobile, Asda Mobile, BT Mobile (BT owns EE!), Lyca Mobile, NOW Mobile, Spusu, Talk Home, Utility Warehouse
O2 : Giffgaff, Sky Mobile, Tesco Mobile
Three : iD Mobile, Honest Mobile, SMARTY, Superdrug Mobile
Vodafone : Asda Mobile, Lebara, Talkmobile, VOXI
Three & Vodafone have merged, might bring future changes.