Asterisk to Asterisk to local PSTN - Want to find out more


I was wondering if somebody could point me in the right direction as a solution to the following. I’m not looking for a complete answer (although that would be nice!) I would just like to pointed in the right direction so I can find the answers e.g. what keywords do I need to search for?

My company has three offices, London, Chicago and Singapore with approximately 20 people in each office. We are looking for a solution that would allow us to make local calls in any of these countries from any of our offices.

E.g. I call a Singapore number from London, my local Asterisk box recognises that it is a Singapore number and transfers my call to the Asterisk box in the Singapore office. The Singapore Asterisk box then dials out to the local PSTN?

I bet there’s some kind of acronym or search term I could use to find a whole load of info on this, unfortunately I don’t seem to be able to find it!

thank you in advance,


Its simple realy, Just standard voice networking.

First link all sites with sip or IAX connections.

then construct a dialplan that for example whenyou dial
9001XXXXXXX it routes the call to the US system and breaks the call out there.

You just have to be careful with security