hi restriction codes is nothing but the mobile is restricted to particular network to solve the problem we can use codes to unlock .you can get the codes from here onlinegsmunlock here they ask
the following details they are mobile model,country and the network which locks your mobile ,imei
number of the mobile .finally they will send the codes to unlock the mobile.once you entered the codes in your mobile your mobile get unlocked and it will be free to accept any network sim.