Multiple sites w/ Asterisk

I work for a small company (less than 50 employees) that has some branch offices in different area codes. We’re hoping to replace our telephone systems in each branch, and with one big system that will link them all together.

I’m thinking of setting up an Asterisk box in each branch office, which would be connected to the PSTN through POTS or a PRI, and then linking the branches together with SIP trunks over our WAN. We would like to have an Asterisk server in each branch, for fault-tolerance purposes.

What I want to know, is how we could use this arrangement to link our branches together. We’re specifically interested in transferring unanswered calls from one branch to ring on telephones in another branch. Other features such as call parking/pickup between branches, and conferencing would also be attractive.

I’ve looked at, but I haven’t found any good information on setting up multiple sites with Asterisk. Can anyone point me in the right direction?

Jared Liebl
MIS Manager
Climatic Control Company, Inc.
(414) 259-9070

Have a look at AMP and the following ‘new’ site also, there’s some explanation regarding “trunking” IAX … I don’t know about the other features (as described above) though… If you do get any steps further, please post or add to the wiki. … umentation


IAX trunking is the solution, you do not have to use AMP.

Especially if you want to retain flexibility in your environment, I recommend using Dundi.
The advantages are that you don’t have to hardcode your IAX trunks in a full-mesh arrangement, (n^2+1 rule applies), and you remain quite flexible.

A valuable source of information is: … ration+IAX

Note: Paradise doesn’t come by itself :smile: I’ve run into a problem with Dundi myself (see thread in the Dundi forum), but as I’m fairly new ad Dundi myself, I expect I goofed somewhere. Once I’ve figured it out, I’ll post my personal idiot guide that should get you going within a couple of hours.

Take care,

Thanks to Stoffell & the others for the advice.

With Stoffell’s help, I found these instructions for setting up an IAX2 trunk between servers: … e=FaqTrunk.

The instructions mention that you may not want to use a dial-prefix on the trunk, and just to use Outbound Routing. After trying it out, I agree. The dial-prefix didn’t seem to work for me.

The advice that LeoS offered about DUNDi seems good, but I’ve got a pretty small operation, and it turns out that setting up an IAX2 trunk isn’t that hard with AMP (I’m currently using Asterisk@Home v1.0).

My next question is this:
Does IAX2 offer any advantages over a SIP trunk? I’m going to be using SIP telephones, so would it be better to just stick with one protocol all the way through, if I can?