What is Sim only?

A sim only plan covers the network side of a mobile deal without a new handset, so you can use a phone you already own or an unlocked device. You pay for calls, texts and data only, and you keep control of the handset. 019 Mobile, 1&1, 1pMobile, 2degrees and 3 Denmark all list sim only options, so if you do not want a new phone you can set that rule out before you compare prices.