That fact makes me seriously doubt their claims of it being "privacy first". Perhaps Phreeli can be taken at their word about their own practices (but remember, we only have their word to go on with this), but T-Mobile is still handling the traffic, and they're not likely to be terribly concerned about user privacy.

Aside from their privacy claims, there doesn't really seem to be anything unusual in their offering. If you're the sort who wants/needs a burner phone, this offering doesn't reduce that need.

This whole article appears to be just a thinly-veiled advertisement.