GPP sim on IOS 7

I have the GPP sim for my sprint iPhone 4S and I was wondering if I could still using the GPP sim on tmobile if I installed the IOS 7 beta. I tried emailing them a few days ago but I still haven't gotten a reply about it. Has anyone gotten it to work and still be on tmobile or whatever service while on IOS 7 if not does anyone know when it will be available?

Thank you