Unlocking Key

i purchased a cheap version of voda fon mobile while i was in plymouth probably from asda,what i know that my pakistani sim of ufon was compatable with vodafon,coz when ever there was problem of signles if use to convert into voda network...but it was in other fone,now in pakistan i want to use it with ufone and when i inserted the ufon sim.its asking for network key,so can u help me in this regard.the model of fon is Vodafone 345 Text