Detecting And Handling E9-1-1 Calls - AudioCodes Mediant 1000B User Manual

Media gateway & enterprise session border controller (e-sbc)

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The figure below illustrates an AudioCodes ELIN device deployed in the Lync Server

environment for handling E9-1-1 calls between the Enterprise and the emergency service

15.8.3.1 Detecting and Handling E9-1-1 Calls

The ELIN device identifies E9-1-1 calls and translates their incoming E9-1-1 calling

numbers into ELIN numbers, sent toward the PSAP. The device handles the received E9-

1-1 calls as follows:

The device identifies E9-1-1 calls if the incoming SIP INVITE message contains a

PIDF-LO XML message body. This is indicated in the SIP Content-Type header, as

shown below:

Content-Type: application/pidf+xml

The device extracts the ELIN number(s) from the "NAM" field in the XML message.

The "NAM" field corresponds to the <CompanyName> column in the Location

Information Server (LIS). The device supports up to five ELIN numbers per XML

message. The ELINs are separated by a semicolon. The digits of the ELIN number

can be separated by hyphens (xxx-xxx-xxx) or they can be adjacent (xxxxxxxxx), as

shown below:

<ca:NAM>1111-222-333; 1234567890 </ca:NAM>

The device saves the From header value of the SIP INVITE message in its ELIN

database table (Call From column). The ELIN table is used for PSAP callback, as

discussed later in 'PSAP Callback to Lync Clients for Dropped E9-1-1 Calls' on page

295. The ELIN table also stores the following information:

ELIN: ELIN number

Time: Time at which the original E9-1-1 call was terminated with the PSAP

Count: Number of E9-1-1 calls currently using the ELIN

An example of the ELIN database table is shown below:

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