Honest question: why would I want to use ptel?

Glancing at them real quick, they're a T-Mobile MVNO and their mid-range unlimited plan is $50/month with 2GB of high-speed data. Straight Talk, which is usually on T-Mobile but depending on device and region also uses the other three major carriers, is $45 for an unlimited plan with 3GB of high-speed data. And MetroPCS, owned by T-Mobile, is also $50/month for a mid-range plan, but with 3GB of high-speed data.

Unless it has better roaming priority, I don't see what it brings to the table (maybe pay-as-you-go is a different story, though, if that's what you're interested in).