It's a hardware where you can insert multiple sims but Im just using the single version(http://www.dbltek.com/products/goip-1.html). We use it as a gsm gateway for outbound calls and freeswitch setup instructions are available in the freeswitch pagehttps://freeswitch.org/confluence/display/FREESWITCH/Goip+HowTo

Do you have an idea whats causing the termination problem?