> The correct answer is no one outside US Government IT knows for sure what is or isn't approved per their own rules
Veterans Affairs actually publishes a list of approved software as part of their Technical Reference Model: https://www.oit.va.gov/services/trm/ (don’t know how complete it is)
But I’m not aware of other agencies doing this. I suppose that VA, given the nature of what they do, likely feels that there is less risk in publicising this information
There’s also the FedRAMP program for centralized review of cloud services - fedramp.gov - I haven’t looked to see if Telemessage is listed as approved but I see some references to FedRAMP and Telemessage online suggesting that it may be
Another source of info is SAM.gov - https://sam.gov/opp/ab5e8a486e074d73bfe09b383ba819ab/view (that’s for NIH) - if there is an agency paying for it, you can assume they’ve approved it for use (or are in the process of doing so) even if they haven’t otherwise publicly said they are. But, not all contracts are public, so just because you can’t find it on SAM.gov doesn’t mean it doesn’t exist