Emergency Services Access (ESA) 319The basic ESA feature only provides for a single ESA route per system.Since all IP Phones are associated with the same main office, all ESA callstherefore go to the same Public Safety Answering Point (PSAP) regardlessfrom which Branch Office they originated. This is not satisfactory if thebranch offices are widely dispersed.In general, ESA calls should leave the network through a trunk at theBranch Office where the originating telephone is located. To enable this,it is necessary for telephones at each Branch Office to supply a uniqueidentifying prefix to the NRS when the ESA calls are being routed so thatthe NRS can select a distinct route for each Branch Office. This prefixcan be configured with the zone data for the MG 1000B telephones. Theprovisioning of this prefix is an enhancement for Branch Office.While a variety of numbering schemes are available, Nortel recommendsthat customers use "0" + the ESN location code of the MG 1000B + ESDN,where ESDN is:• for North America and CALA — "911"• for members of the European Union — "112" and any other emergencynumbers in use prior to the EU directiveThis number, referred to here as the ESA Special Number, is configured asa special number (SPN) in the NRS so that the Virtual Trunk routes the callto the Branch Office.Procedure 37Configuring the main officeStep ActionYou can use Element Manager or the Command Line Interface for thisprocedure. Refer to IP Peer Networking Installation and Commissioning(NN43001-313) for details.1 Configure the main office emergency trunk (CAMA or PRI).Configure either analog CAMA or digital PRI to correctly signal thecall identification.ESA overrides all security features. Configure the trunk withrestrictions so that other features cannot access the trunk.2 Configure the Virtual Trunk using the procedure from IP PeerNetworking Installation and Commissioning (NN43001-313) .The Virtual Trunk must be configured to enable emergency callsoriginating from MG 1000B IP Phones registered at the main officeto reach the Branch Office.3 Configure ESN.Nortel Communication Server 1000Branch Office Installation and CommissioningNN43001-314 01.02 StandardRelease 5.0 20 June 2007Copyright © 2007, Nortel Networks.
