This is probably the same caller ID problem discussed in your other thread. If so, you either need to fix the issue of sending numbers that are not yours, or do the reroute with a Ring Group or other means where you can force the outbound caller ID to be a company number.
Another possibility is a limitation on the number of simultaneous calls permitted on the trunk, imposed by the trunking provider or by configuration set in the PBX.
Finally, it’s possible that the inbound trunking provider requires (at least) a Ringing or Progress signal within e.g 5 seconds, and the setup time for the outbound leg is longer than that. Using a Ring Group would avoid that.
Look at the Asterisk log for a failed call. If "Called " (without the quotes) appears, the call was sent to the trunk and rejected by the provider. If not, FreePBX rejected it, possibly by counting channels incorrectly.
If the provider rejected the call, at the Asterisk command prompt type pjsip set logger on
or sip set debug on
according to trunk type. Make another failed call – the response to INVITE should give a clue as to why the call was rejected.