Asterisk Trunk for Termination

I'm working with call terminations. Our customers subscribe our service like a regular SIP provider. We receive the calls via SIP or IAX2. The calls reach our asterisk server and we need to decide wich is the best option of provider to complete the call. To do that, we take the number receive as incoming call, search in our MySQL database to find out which is the best service provider. If we don't find on our database, we will check outside, via URL search the provider. When we have the provider defined, we send to the right trunk. We have this solution working today, running Asterisk 11.5.1 and FreePBX 2.11. But we are facing some issues with the solution: sometimes the calls are being cancelled. We are looking some professional that is able to fix the issue with the actual environment or propose a new environment (pure Asterisk) and deliver the solution working. Professionals with similiar projects will be preferred. If additional information is required I'll provide. If its necessary take a look in our environment to establish a more concise scope, we can discuss this and arrange it.