Message Waiting Indication

The device supports Message Waiting Indication (MWI) according to IETF RFC 3842. The device also supports subscribing to an MWI server (using SIP SUBSCRIBE messages).

For more information on configuring IP-based voice mail, refer to the IP Voice Mail CPE Configuration Guide.

To configure MWI, use the following parameters:

■ EnableMWI
■ MWIServerIP, or MWISubscribeIPGroupID and ProxySet
■ EnableMWISubscription
■ MWIExpirationTime
■ SubscribeRetryTime
■ SubscriptionMode
■ VoiceMailInterface
■ EnableVMURI

The device supports the following PSTN-based (digital) MWI features:

■ Euro-ISDN MWI: The device supports Euro-ISDN MWI for IP-to-Tel calls. The device interworks SIP MWI NOTIFY messages to Euro-ISDN Facility information element (IE) MWI messages. This is configured by setting the VoiceMailInterface parameter to 8.
■ ISDN PRI NI-2: The device support the interworking of the SIP MWI NOTIFY messages to ISDN PRI NI-2 Message Waiting Notification (MWN), sent in the ISDN Facility IE message. This is applicable when the device is connected to a PBX through an ISDN PRI trunk configured to NI-2. This is configured by setting the VoiceMailInterface parameter to [9].
■ QSIG MWI: The device 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 voice mail capabilities and a softswitch, which requires information on the number of messages waiting for a specific user. To enable this feature, use the 'MWI Interrogation Type' parameter in the Trunk Group Settings table, which defines the device's handling of MWI Interrogation messages. The process for sending the MWI status upon request from a softswitch is as follows:
a. The softswitch sends a SIP SUBSCRIBE message to the device.
b. 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.
c. 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.
d. The device sends another SIP NOTIFY to the softswitch, containing this MWI information.
e. The SIP NOTIFY messages are sent to the IP Group defined by the [NotificationIPGroupID] parameter.

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 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., doesn't 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.