Could someone point me in the right direction on the cleanest method to be able to use the built-in Outgoing Routes feature of FreePBX (specifically, the trunk sequencing) when making ARI/AMI originate requests? Or, do you recommend to just create my own script to failover to other SIP trunks (congestion, trunk offline, etc)?
With AMI Originate, specifying a Context of from-internal will cause the call to follow Outgoing Routes, trunk sequencing, etc., just like a call from a normal extension.
With operations (Dial, etc.) where you would specify a technology such as PJSIP or IAX2, you can use the special channel Local instead, to cause normal dial plan to be executed.