Trunks are external lines that provide the physical connection between a Norstar system and other systems in a private or public network. Trunks are numbered 001 to 156 in a fully expanded system. Norstar Modular ICS supports six different types of trunks:
• PRI trunks are used for incoming and outgoing calls over an ISDN network. PRI SL-1 lines can provide MCDN network functionality in a private network between other Norstar systems, Meridian 1 systems, or Business Communications Systems, if the appropriate software code has been installed.
• T1 trunks are digital trunks that can be configured to act as loop start, ground start, EM, DID, or leased lines, depending on your requirements.
— DID trunks route incoming calls from the public network directly to telephones within Norstar, without an attendant.
— Loop start trunks handle incoming and outgoing calls
between Norstar and the public network.
— EM trunks handle incoming and outgoing traffic between the Norstar system and the private network.
• BRI trunks handle incoming and outgoing calls between Norstar and an ISDN network.
• Target lines are virtual communication paths between trunks and telephones on the Norstar system.