HowTo interconnect two sipX PBXs

From SIPfoundry sipXecs IP PBX, The Open Source SIP PBX for Linux - Calivia

Setup sipXecs to sipXecs Calling

To enable calling between 2 (or more) sipXecs PBX's there are three steps:

• Make sure each PBX can resolve pertinent DNS records for each other's domain (SRV if you are using SRV).

• If the servers are behind NATs, make sure that you have enabled remote access as though you were setting up to allow remote workers. See Configuring remote workers cheatsheet.

• Setup an unmanaged gateway on each PBX pointing to the other PBX.

• Setup a dial plan to direct calls to the other PBX - use the 'site-to-site' dial plan type.