AudioCodes Mediant 800B User Manual page 444

entity (for example, another ELIN Gateway), instead of retrying the call or returning the
release call to the user.
To support this requirement, the ELIN Gateway can be configured to send the 503 "Service
Unavailable" release cause code instead of SIP 4xx if an emergency call cannot be
established. To enable this support, the following ini file parameter setting must be done:
Note:
EmergencySpecialReleaseCause.

To enable SIP response 503 upon failed E911:
1. Open the Advanced Parameters page (Configuration tab > VoIP menu > SIP
Definitions > Advanced Parameters).
2. From the 'Emergency Special Release Cause' drop-down list, select Enable.
26.11.4.4.4 Configuring Location-Based Emergency Routing
The device identifies the geographical location of emergency callers by their ELIN
numbers, which is present in the PIDF-LO XML body of received SIP INVITE messages.
Therefore, you need to configure the device to route emergency calls to a destination (i.e.,
emergency center such as police) that is appropriate to the caller's ELIN number. As the
destination of incoming calls is the emergency number (e.g., 999), the device needs to
manipulate the destination number to a number that represents the caller's local
emergency center (e.g., +4420999 for London police).
To add manipulation rules for location-based emergency routing, you need to use the
Destination Phone Number Manipulation Table for IP-to-Tel Calls table. In this table, you
need to use the ELIN number (e.g., 5000) as the source prefix, with the "ELIN" string value
added in front of it (e.g., ELIN5000) which is used internally by the device to identify the
number as an ELIN number (and not used for any other routing processes etc.). For each
corresponding ELIN source number prefix entry, you need to configure the manipulation
action required on the destination number so that the call is routed to the appropriate
destination.
Following is an example of how to configure location-based emergency routing:

Assumptions:
•
Company with offices in different cities -- London and Manchester.
•
Each city has its local police department.
•
In an emergency, users need to dial 999.
•
Company employs Microsoft Lync for communication between employers, and
between employers and the external telephone network (PSTN). In other words,
all employers are seemingly (virtual) in the same location in respect to the IP
network.
•
ELIN numbers are used to identify the geographical location of emergency calls
dialed by users:
♦
♦

Configuration Objectives:
•
Emergency calls received from London office users are routed by the device to
the London police department, which is +4420999.
•
Emergency calls received from Manchester office users are routed by the device
to the Manchester police department, which is +44161999.
User's Manual
This can also be
London ELIN is 5000.
Manchester ELIN is 3000.
Mediant 800B Gateway and E-SBC
configured using
444
the ini file parameter,
Document #: LTRT-10286