Dial Plan Design with Multiple Asterisk

Hi Everyone,

I’m designing a Cisco Call Manager replacement with Asterisk. The scenario is the following:

One main site and three remote sites.

The main site with an Asterisk with a PRI-E1 connected to the PSTN to handle all the inbound calls for the four sites, and with another PRI-E1 connected to a GSM channel bank to handle all the outbound calls to mobile phones from the four sites.

Another Asterisk on the main site will register all the SIP phones and two 24-port analog AudioCodes gateways.

On every remote site, an Asterisk with a PRI-E1 connected to the PSTN will handle all the outbound calls for every site (except for mobile phone, in that case will use the channel bank on the main site) and will handle all the SIP phones and ATAs on every site.

We need to be transparently to the users, and my concern is about for example, we have a 4031 extension on main site, a 4032 extension on site 2 and 4033 extension on site 3; and can’t change that. How must i configure the outbond routes on the main site, if the extension 4032 on site 2 has to call extension 4033 on site 3, but going through the main site? or do you suggest to create outbound routes on every remote Asterisk directly to all other Asterisk?

Thanks in advance for your help.

Same extension numbers on different locations are usually solved with adding prefixes if a user wants to call an extension on another location. For example, let say that a user 4002 on central location wants to call:

  1. Extension 4033 on location 1 - dials 14032

  2. Extension 4033 on location 2 - dials 24032

If you have this kind of system, you can eazily make routing tables on all Asterisk servers, so internal calls via locations flow as they should.