Hello all,
We are using Telnyx with IP authentication. We are able to receive calls however not able to place calls. We have been using Bandwidth for trunking in the same method and don’t have any issues. Any suggestions? Not too sure what information would be helpful - please let me know what you need 
Confirm that destination number (assuming call to US) and caller ID sent to trunk are 11 digits.
Confirm that your public IPv4 address is properly set on Telnyx portal.
If no luck,
At the Asterisk command prompt, type
pjsip set logger on
make a failing test call, paste the Asterisk log for the call at pastebin.freepbx.org and post the link here.