Hello, I'm a voip specialist with 10+years of experience working on the level2/NOC department of a US voip company; I can install, troubleshoot and customize many SIP devices including softphones, ATAs, IP-phones and PBX systems like Asterisk/FPBX. I read your project description, and If I understood it correctly, you want to connect Asterisk(R) and (B) together so calls initiated from (R) are terminated using Goip box trunk on (B) is that correct ? Feel free to contact me at any time so we can go through more details.
Thank you.