How can I active another sim?
You can activate as many SIMs as you like on GiffGaff for many different devices, however each must be registered on its own GiffGaff account as you can only have one Sim/Number per account
You can not have 2 Sims with the same number or in the same account, each must be unique!
You can order a new FREE SIM card from https://giffgaff.com/activate link to the activation page and enter the 6 digit activation code from a new GG SIM card. Click (Activate your SIM) then register a new account (do not log into your existing account)A new account will mean a new phone number!