Hello,
Im new to the Asterisk world. I have successfully setup a local Asterisk server at office on a CentOs machine , and it works well on our office LAN .
Now, another branch of our office is located in another city . How can i allow access to people over there to my local asterisk server running at office so that they can place calls through the server too .
What setup will be needed ?
Thank You. 
It would depend on how the two offices were networked together, e.g. a private network, a VPN, or through the public Internet. Do you want two Asterisk servers connected together, or the remote office users to connect their phones directly to a single Asterisk installation? The book has details on how to connect two Asterisk servers: http://downloads.oreilly.com/books/9780596510480.pdf
Ian
Thanks for the reply plmco . The remote office does have VPN connectivity to our network. What id like to be able to do is the latter case that is allow the remote office users to connect their phones directly to the Asterisk installation at my end .
Can they configure their X-Lite softphones for this ?
Any help with this would be greatly appreciated .
Thank You.
It should indeed be possible, X-lite just needs to be configured with the address of the Asterisk machine on the VPN. However, VPNs tend to use quite a lot of bandwidth, so depending on your network speeds, you might have call quality issues running over a VPN. If both offices have Internet connections and the Asterisk box is accessible from outside, you might be better off bypassing the VPN. You will probably have to configure your router/firewall to let sip and rtp traffic through to Asterisk.
Ian