Hello, I'm a voip specialist with over 10 years of experience working on the TS department of a VOIP company; I can install, troubleshoot and customize many VOIP devices including: softphones, ATAs, IP-phones and PBX systems like Asterisk/FPBX. I read your project description and I can help you build your customized fail-over route/dial-plan. I'm available through chat at any time.
Thank you.