Conference room

Hi guys,
I have 2 trunks, one for external calls and the other one for internal calls with the other our office, that is in another city. The internal and external calls work fine.
Now I’m trying to configure a conference room. If from an extension that is in my office I call the extension of the conference room, it’s ok, but when an extension of the other office try to do it, the caller is forwarded to another extension that is in his office and I, via putty, cannot see any log from asterisk.
Can you kindly help me?
In my office we have Asterisk version 11.7.0 with Elastix, version 5.2.1. Instead in the other office they have only Asterisk. I don’t know exactly which version, but maybe 1.8.
I hope I have explained clearly.



Check you dialplan.