Emergency E911 Phone Number Services; Pre-Empting Existing Calls For E911 Ip-To-Tel Calls - AudioCodes Mediant 3000 User Manual

User's Manual
interworks SIP MWI NOTIFY messages to Euro-ISDN Facility information element (IE)
MWI messages. This is supported by setting the VoiceMailInterface parameter to 8.

QSIG MWI: The device also supports the interworking of QSIG MWI to IP (in addition
to interworking of SIP MWI NOTIFY to QSIG Facility MWI messages). This provides
interworking between an ISDN PBX with voicemail capabilities and a softswitch, which
requires information on the number of messages waiting for a specific user. This
support is configured using the TrunkGroupSettings_MWIInterrogationType
parameter(in the Trunk Group Settings table), which determines the device's handling
of MWI Interrogation messages. The process for sending the MWI status upon request
from a softswitch is as follows:
1. The softswitch sends a SIP SUBSCRIBE message to the device.
2. The device responds by sending an empty SIP NOTIFY to the softswitch, and
then sending an ISDN Setup message with Facility IE containing an MWI
Interrogation request to the PBX.
3. The PBX responds by sending to the device an ISDN Connect message
containing Facility IE with an MWI Interrogation result, which includes the number
of voice messages waiting for the specific user.
4. The device sends another SIP NOTIFY to the softswitch, containing this MWI
information.
5. The SIP NOTIFY messages are sent to the IP Group defined by the
NotificationIPGroupID parameter.
In addition, when a change in the status occurs (e.g., a new voice message is waiting
or the user has retrieved a message from the voice mail), the PBX initiates an ISDN
Setup message with Facility IE containing an MWI Activate request, which includes
the new number of voice messages waiting for the user. The device forwards this
information to the softswitch by sending a SIP NOTIFY.
Depending on the PBX support, the MWIInterrogationType parameter can be
configured to handle these MWI Interrogation messages in different ways. For
example, some PBXs support only the MWI Activate request (and not MWI
Interrogation request). Some support both these requests. Therefore, the device can
be configured to disable this feature, or enable it with one of the following support:
•
Responds to MWI Activate requests from the PBX by sending SIP NOTIFY MWI
messages (i.e., does not send MWI Interrogation messages).
•
Send MWI Interrogation message, but don't use its result. Instead, wait for MWI
Activate requests from the PBX.
•
Send MWI Interrogation message, use its result, and use the MWI Activate
requests.
26.5

Emergency E911 Phone Number Services

This section describes the device's support for emergency phone number services.

26.5.1 Pre-empting Existing Calls for E911 IP-to-Tel Calls

If the device receives an E911 call from the IP network destined to the Tel, and there are
unavailable channels (e.g., all busy), the device terminates one of the calls (arbitrary) and
then sends the E911 call to that channel. The preemption is done only on a channel
pertaining to the same Trunk Group for which the E911 call was initially destined and if the
channel select mode (configured by the ChannelSelectMode parameter) is set to a value
other than "By Dest Number" (0).
The preemption is done only if the incoming IP-to-Tel call is identified as an emergency
call. The device identifies emergency calls by one of the following:

The destination number of the IP call matches one of the numbers defined by the
Version 6.6
26. Configuring Supplementary Services
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