Default Verizon S3 on Metro PCS help.

So I'm helping a friend with her S3. It is a Verizon phone but we have it working on Metro. Problem is data is really slow and error message "unknown Sim card" in status bar. Everything works but just trying to get full 4g and get rid of the Sim card error. It is rooted so if a system file needs to be deleted or altered it can be done.

Thanks


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