My company already has a Aastra PBX handling all their extensions. I have installes a Asterisk VOIP pbx, because they slowly want to switch over to the new system.
For now only one part of the office is using the Asterisk server, 4 extensions. (200-204). Thats the same extensions numbers they had previously with the Aastra PBX. The rest of the office are still on the Aastra pbx with extensions (205-400).
How can I go about setting it up so that someone on the Asterisk server can call a extension on the Aastra PBX ?