What Do the Following Cisco Commands Mean?

A trunk (tie-line) is a permanent point-to-point communication line between two voice ports. The connection trunk command creates a permanent Voice over IP (VoIP) call between two VoIP gateways. It simulates a trunk connection through the creation of virtual trunk tie-lines between two telephony endpoints. To the connected systems, it appears as if a T1 trunk is directly connected between them.

For the rest of the story go to http://www.cisco.com/warp/public/788/signalling/trunk_config.html