Implied MWI Subscriptions

For a phone to receive notification of message events, it first has to send a subscribe message to the sipX server. If a phone sends a SUBSCRIBE for the message-summary event package, it will get notification (see Enabling MWI Notification).

There are phones that don't send the SUBSCRIBE (i.e. Cisco), but will still present an indication if they are sent an unsolicited NOTIFY (an early version of the internet-draft apparently allowed for this - it is not a part of the RFC, and don't let phone vendors tell you it is - they should SUBSCRIBE). There is some provision for this in the sipXregistrar; it is a hack, but it sometimes works. I don't think there is a GUI for configuring it (config server people?), but you can edit the file:

you will find a directive there by default that configures this for Cisco phones:

to add support for another phone, create a new directive:

where FOO is just a unique name (each configuration parameter must have a unique name), and the '^fooagent' is a perl regular expression (that does not contain blanks) that will match the value sent by the phone in the User-Agent header of its REGISTER message. The registrar will then try to create a subscription on behalf of the phone. You should NOT do this if the phone does do a SUBSCRIBE, because it may be confused by the extra NOTIFY messages it will get.

Incidentially, newer Cisco versions apparently have changed the User-Agent header, so you might need to change them to:

Reports of configuration that works for different phones (include the firmware version numbers please) are most welcome.

Note: This feature is turned on by default if you configure a Cisco phone using Configuration Server and the MWI feature should work "out-of-the-box".

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