Audiocodes Elin Device For Skype For Business E9-1-1 Calls To Pstn; Detecting And Handling E9-1-1 Calls - AudioCodes Mediant 4000 SBC User Manual

CHAPTER 16 Services
AudioCodes ELIN Device for Skype for Business E9-1-1 Calls to
PSTN
Microsoft Mediation Server sends the location information of the E9-1-1 caller in the XML-based
PIDF-LO body contained in the SIP INVITE message. However, this content cannot be sent on the
SIP Trunksince they do not support such content. To solve this issue, Skype for Business requires
a (ELIN SBC) to send the E9-1-1 call to the SIP Trunk. When Skype for Business sends the PIDF-
LO to the , it parses the content and translates the calling number to an appropriate ELIN. This
ensures that the call is routed to an appropriate PSAP, based on ELIN-address match lookup in the
emergency service provider's ALI database.
The figure below illustrates an AudioCodes ELIN device deployed in the Skype for Business
environment for handling E9-1-1 calls between the company and the emergency service provider.

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:
1. 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
2. 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>
3. 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 Skype for Business Clients for Dropped E9-1-1
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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Calls. The ELIN table also