How to call main conference room from branches

[hullc65203]

I've got 5 offices located in different cities, all connected by MPLS network. I'm trying to set up Asterisk as my phone system. Each branch has it's own Asterisk server with trunks for local calling. I want to add 2 things: allow extensions in office A to use the directory in office B, and 2: allow extensions from all offices to access conference rooms in office A.

I've installed AsteriskNow and am using FreePBX.

[RonaldS]

Can this be done using Asterisk? Can't the extensions be programmed to dial out if you are in office A and you are dialing an extension for office B? For instance, if you dial extension 3243, it will recognize the extension is not in office A and will add the are code and the rest of the number to 3243. It would be kind of like shortcuts or speed dial numbers on cell phones. Is that possible? Or can this be done on other voip phone systems?