Before leaving the country,visit any Ooredoo branch and make sure you pay their dues,and the best thing is to cancel the service and when you come back you can apply new connection,reason...you never know your landlord might cancel the building while you are away and he'll report you as runaway with his dues as well as Qtel...and then Interpol will hunt you down if you're out of Qatar..however you'll be blocked in the airport can't Exit..