With federal inmate texting, messages are relayed using the federal Corrlinks/TRULINCS components

https://prisontextapp543.rivetgarden.com/posts/federal-inmate-text-app-vs-corrlinks-text-app-key-differences-explained

With federal inmate texting, messages are relayed simply by the federal Corrlinks/TRULINCS formulation, and replies can return to the backyard user as long-established text messages.