Iphone 6s Plus SIM Card Problem

Hello so today I had went in to get an iphone 6s Plus 64gb I got it through their financing problem and I was approved. Now the problem here is that I purchased the Factory Unlocked version so I'd be able to connect with any carrier of choice. But upon trying to use my metroPCS SIM card it says no service. Although when I head into my settings>general>network it says Not Available then once I had clicked on it, it says the following Phone is not allowed anyone know any possible solutions to this?