52 OverviewLocal Mode at the Branch Office, the MG 1000B telephones remain in LocalMode, displaying aServer Unreachable (1) message and receives all callprocessing services from the CP PM in the MG 1000B Core.MG 1000B IP Phones in Normal Mode remain registered with the main officewhen the Primary NRS fails and no Alternate or Failsafe NRS is available.They can call any main office telephone or IP Phones in Normal Mode inother branch offices. However, they cannot call any MG 1000B digitaltelephones, analog (500/2500-type) telephones, or any external numberthrough the MG 1000B trunks in the normal way, because the Virtual Trunksare not available. (MG 1000B digital or analog (500/2500-type) telephonesare accessible if alternate routing is available through the PSTN.) The userhas the option of staying in Normal Mode, or going to Local Mode manuallyby resetting the telephone or using Test Local Mode. In Local Mode, theIP Phones can make local calls to other IP Phones, digital telephones, andanalog (500/2500-type) telephones at the Branch Office. They can also beused to make outgoing PSTN calls as usual.You must plan for, and obtain, the Primary and optional Alternate NRSaddresses for installing the Branch Office feature software. Determine theNRS role, that is, the Alternate or Failsafe configuration, for the MG 1000BSignaling Server.Nortel recommends that the NRS in the MG 1000B be configured as aFailsafe NRS, unless it is already acting as the Primary or Alternate NRS.If the MG 1000B IP Phones go into Local Mode, they can use the MG1000B NRS services.For CallPilot Mini and CallPilot 201i applications, a Message WaitingIndication (MWI) does not survive a Mode change (Normal to Local or Localto Normal). The message itself is preserved, but the lamp indicator may notbe lit after the Mode change.Active Call FailoverThe Active Call Failover (ACF) feature for IP Phones allows active IP calls tosurvive the following failures:• IP/IP calls and IP/TDM calls survive signaling path TLAN subnet failures.• IP and IP/TDM calls survive Signaling Server restarts.• IP and IP/TDM calls survive LTPS ELAN subnet failures.• IP calls survive a Call Server cold start and Call Server failures insystem configuration with a redundant Call Server.ATTENTIONAll IP Phones excluding Phase 1/0 support Active Call Failover.Nortel Communication Server 1000Branch Office Installation and CommissioningNN43001-314 01.02 StandardRelease 5.0 20 June 2007Copyright © 2007, Nortel Networks.
