How to fix Messages and FaceTime activation issues on Government-Issued iPhone

I am not receiving messages and my iMessage or FaceTime with not activate. How do I fix this? This is a government cell phone and I need this for work.

This Is a government Army Recruiting cell phone that I use daily for work. I sent out over 300 messages and received a message that said IMessage Activation Failed. I am not receiving all my messages and need this fixed. Thank you

[Edited by Moderator]