Looking through the forum, I assume in order to route specific trunks by the extension I will need a custom extension. Is this correct, or am I missing a setting?
It depends on what you want to do. Would adding a prefix to a route where you would assign the trunk and having extension dial it be enough, or you want to force calls from a particular extension or a group of extensions to a specific trunk?
Third Lane Technologies
Multi Tenant Asterisk PBX
Alex... I'm looking to do the latter... "force calls from a particular extension or a group of extensions to a specific trunk".
you can still do this the same way. lets say you make pattern _71*NXXNXXXXXX to use trunk2. You could easily modify the digitmap/dialplan on those devices to take a 10 digit number and add 71* in front of it, etc. each device does it differently but that is a matter of looking up the manuals for those devices. I did this for someone's ATA that went to some call box. They wanted to force its traffic out a specific trunk, so we altered the 1xxxxxxxxxx and xxxxxxxxxx patters to prepend the extra digits.
Thirdlane/Asterisk Support available
I thought of that, but these are fax "extensions" that I need to route. In short, we have two providers and one of them has slight better quality which would likely lead to fewer errors.
If you don't mind creating and using your own script for dialing out, you could add tag to the extensions (advanced tab on the extension page), and then do whatever you need in the script. i.e. prepend digits based on the tag presence, or just use tag as the "prepend digits" and have the route defined accordingly.