96 / Dialing plansModular ICS 6.0 Installer Guide P0992638 03Dialing plan using public linesFor example imagine that you have a system in a network ofthree offices such as New York, Toronto, and Santa Clara.If there is no routing, callers would have to dial this way:• A Norstar user in New York would have to select a linepool and dial a number such as 1-416-555-3227 to reachtelephone 3227 in Toronto (416).If there is routing:• you could create a destination code of 3, and create a routethat uses the proper line pool and DialOut. In this case, theuser simply dials 3227, the receiving telephone DN being227.In the DialOut, P stands for pause, a host system signallingoption. Press ²à¡ to insert a 1.5-second pause in thedialing string. See the Modular ICS 6.0 System CoordinatorGuide for information about other signals.Destination code numbering in a networkBecause the system checks the initial digits of a call against therouting tables, each type of internal or external call must beginwith a unique pattern of digits. The following table gives asample plan for how initial digits are assigned in a network ofsystems with three-digit DNs.Leading Digits Use0 Network Direct Dial221-253 (default) Intercom calls (DNs)4 Coordinated Dialing Plan5 Unused6 Unused8 Call Park Prefix9 All PSTN Calls