I would like to purchase unlocked iphone?

My friend bought iphone under contract and after it he unlocked it with out paying to company from local market shop. Now all network is working in his mobile and He would like to sell his mobile at cheaper rate. And would like to go for another one so shell i have purchase his mobile.

Have i any problem from that network company?

If you plan on switching carries (for example he was on at&t and you wan to put it on verizon) then probably. When you buy a phone through a carrier it is usually locked onto their network and the only way to switch is to unlock it which someone usually has to do as it takes some additional skills. Carriers do this so you stay on their network. Now my mom had an iphone and once her contract was up she gave it to me and it worked fine (and it should if you don't switch carriers which i didn't). Depending on the carrier your friend had it on, it may or may not work woth other carriers but should work fine if you use the same carrier

Hope that helps

Thank you for your replay
i check it out that all carriers is working on that mobile after unlocked.
but i have to know is there any chance of all service is stop if he do not pay contract charge to carrier company or not.