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Is your organization in the midst of planning for VoIP? One of the most important things to consider while you’re still in the planning stage is how to properly set up the network for E911.

An Emergency Location Identification Number, or ELIN (known as ELE in an Avaya environment) is a designated number that represents one or more telephone endpoints in order to locate an individual who has dialed 911 from a Multi-Line Telephone System (MLTS). This single ELIN can represent several endpoints, especially if there are many within an open office space and few obstructions. The geographical area in which the endpoints exist is called the Emergency Response Location, or ERL. The emergency responder at the Public Safety Answering Point must be able to call back the ELIN in case the caller is disconnected; the MLTS must then be able to deliver the return call back to the original endpoint in order to locate the emergency.

When an organization is transitioning to VoIP/SIP, it is crucial to take into consideration the best scenario for ELIN’s and ERL’s. As VoIP allows for movement of phones, tracking that movement presents a problem. When a phone is moved from one floor or building to another the switch can recognize this movement, but only if the subnet/VLAN has previously been setup to accurately represent the ERL.

During the initial setup of an IP-PBX, if E911 is not addressed when configuring the subnets/VLANs it is likely that problems will be created when E911 is finally addressed. If a subnet has been organized in a way that includes multiple floors, a large area with many barriers, or even multiple buildings, then the entire network may need to be reconfigured and broken down into areas (ERL’s) that make sense for E911.

If an organization includes the step of ensuring that the ELIN and ERL configuration makes sense for E911, a great deal of headache, time and money will be saved in the long run.

For more information on addressing E911 when moving to VoIP/SIP, contact 911 ETC at info@911etc.com or visit http://www.911etc.com.