O2 have been established for a long-time, going back to the early days in the late 80's early 90's when they first launched their GSM network in the UK under the name of "Cell-net" or "Cellnet". They were hugely popular and with wide coverage in the UK. They then merged with BT and went by the Brand "BT Cellnet". They then went from strength to strength and finally changed their brand to what we now know as O2 or 02. O2 are now able to offer their customers plenty of value combined with great flexibility, they remain customer focused with great SIM Only Offers including the like of the "O2 Simplicity SIM Plan" which is by far a popular choice amongst the SIM Plans offered from the O2 network. As the only network to have exclusively sold iPhone connections initially, they continue to also offer great value O2 Micro SIM contracts or iPhone SIM Only Plans. This is also the case for BlackBerry SIM Plans, which can also be found with O2. We compare all the great SIM Plans with O2 including the O2 Simplicity which will give you great value should you choose to go with O2 for your SIM. You also have the choice of 30 day rolling contracts to give you the freedom that you need. Take a look at O2's great SIM Only Offers.