it is well established that the opposite is possible that topping up gigffgaff sim with o2 voucher is possible however imy question is would it be possible to top up an o2 sim with a giffgaff voucher code.??
I have sourced verious forum threads that are full of contradictional information of yes you can, no you cant.
Could anyone say for sure if it is possible, I had bought a giffgaff voucher for a friend who decided to stay with o2 after been offerd dscounted product.
