20 Chapter 2 Introducing SRG200/400 Release 1.5N0075588N0075588Coordination with the main office call serverConfiguration of the SRG branch office requires datafill at both the SRG and the main office callserver. Main office configuration drives SRG configuration, and Nortel recommends that the mainoffice activities be concluded before undertaking SRG configuration.SRG operating modesThe IP Phones can be in either of two operating modes:• Normal mode• Local modeNormal modeIn normal mode (see Figure 1), the SRG is connected to the main office call server over a WANusing VoIP trunks. From the perspective of the main office, the SRG is a branch office. IP Phonesredirected to the main office operate in normal mode.Target Lines Target lines are internal, virtual paths between trunks and telephones for incoming calls(only). They provide flexibility in the way trunks and telephones can be associated: targetlines can be used to direct an incoming call to one or more telephones, direct one ormore trunks to one phone, or direct several trunks (in a line pool) to one or more phones.Target lines are assigned to DNs. A target line triggers ringing voltage to the telephone(s)connected to the port(s) associated with the DN(s) that the target line is assigned to. (Forexample, if a unique target line is assigned to each DN, only one telephone rings whenthe DN is called. If several DNs are assigned to one target line, calling any of the DNsring all of the associated phones.)Target lines are required for auto-answer trunks. Because VoIP lines are set internally toauto-answer, target lines are required for SRG operation.BCM Element Manager provides two methods for assigning target lines to DNs.1) EM: Configuration > Telephony > Sets > All DNs > All DNs table > Details for DNsubpanel > Line Assignment tabor2) EM: Configuration > Telephony > Lines > Target Lines > Target Lines table >Details for Line subpanel > Assigned DNs tabThe first method provides a convenient way to assign the target line to the DN when theDN record is configured. The second method provides fields that allow incoming digitstrings to be mapped to the DN.(Lines 125 to 268)For more information on target lines, refer to the BCM 4.0 Networking ConfigurationGuide.Line pool Several of the same type of trunk configured as one group: a trunk group.Table 5 SRG200/400 Release 1.5 terminology (Sheet 3 of 3)Term Description