O2 Sim Offers Sim only deals are popular especially among those who already have an existing phone. In order to activate the phone, they will get a sim card only plan such as the famous O2 sim only plan. You can find O2 sim only deals both offline and online so it is quite easy to get one. Check out the online stores for more bargain as usually there have additional discount if you purchase online. There are many great reasons why you should get O2 sim only offers and the main one is the savings on your pocket!