Connecting 2 Asterisk server

Hi
I want to connect one Asterisk server (A) in one city to another Asterisk server (B) in another city. for example extension 200 on A wants to call to 400 on B asterisk.May guide me for this purpose ?
thanks for any help or guidance

Hi nima0102,

There are a few ways to do it.

Here is the book;
downloads.oreilly.com/books/9780596510480.pdf

Read chapter 4
Connecting Two Asterisk Boxes Together via SIP
Connecting Two Asterisk Boxes Together via IAX

Brett