MTN VTU Airtime Recharge offers you the ability to top up your MTN SIM . Airtime balance & validity can be checked by dialing *556#. It works on all phones Android phones, Blackberry 10 devices, Iphones, Ipads, Tablets, Modems, Windows phones, java, Symbian, etc. Instant Airtime Transfer to the phone number supplied. Be assured of the best quality call and SMS connectivity with the network that connects people.