I am using Flowroute with 3CX and I can receive SMS but when I send I get this message. I have used the manual and redone all my settings a few times. Any suggestions?
Could you try sending one more message and this time keep track of the exact time you sent it?
Then please send me a PM with this information, as well as your 3CX FQDN so I can try and check if it is something on our side, or if you need to contact Flowroute.
I'm sure there's lots of solutions. Switching providers could be considered a solution. As you are a Gold Partner I recommend opening a ticket with 3CX support.