Dear Sir;
My name's Javier Aguilar, I'm Systems & Telecom. Engineer with +20 years experience in Systems Administration, IT projects management, server management, DataCenter management, Help Desk, Networking engineering design, deployment and troubleshooting, LAN/WAN/SD-WAN/MAN management, and other IT topics.
Ok, I review your project, I guess that you can deploy with all your hardware a new Asterisk PBX or buy a IP PBX box (like Grandstream) for around $ 550 (on Amazon), as a best solution, low power consumption, without noise environment, and fully compatible (as you, we use differents Asterisk deployment for our company from 2006, like pc/server with Asterisk/FreePBX and Digium cards, then pc/server with Elastix -an Asterisk opensource solution- and Digium cards, finally we buy an Grandstream UCM6208 and no more problems and random issues). If you like, contact me by chat before a decision for more details. I'm online right now.
Best regards,
Javier Aguilar
IT Business Corp.
Montevideo, Uruguay, South America (GMT-3:00).