Free O2 Sim Cards | Complete the form on the official o2 website and you'll get 500 FREE texts each month. Or, if you like to talk more than text, you may prefer one of the other free allowances with their Online Pay & Go SIM. Choose either 100 FREE anytime UK network minutes or 150 off-peak any UK network minutes each and every month - the choice is your's. Details of how to select the option you prefer will be sent to you with your Free O2 SIMs. Whichever you choose, you will also receive 1MB free browsing and downloading every month, and lots more with your Free O2 Sim Cards.