As far as I know the French government used a riot fork for their users but the changes are getting upstreamed. I think its not unrealistic that the Bundeswehr will go a similar way
The NSA used XMMP too https://www.google.co.uk/amp/s/www.vice.com/amp/en_us/articl...
I know of a few other non-US government agencies that did that too.
Some countries even run their own MVNO’s for government uses no need to reinvent the wheel.