The TeleMessage archiving backend through 2025-05-05 accepts API calls (to request an authentication token) from the TM SGNL (aka Archive Signal) app with the credentials of logfile for the user and enRR8UVVywXYbFkqU#QDPRkO for the password.
https://www.theregister.com/2025/05/05/telemessage_investigating/