Asterisk sip subscribemwi

Determines how Asterisk informs a SIP client about voicemail messages.
Some devices, like those made by AVM (Fritz!Box) or Siemens Gigaset (DECT), are known to benefit from subscribemwi=yes.

Details

Asterisk will normally send the NOTIFY for MWI even if the device doesn’t subscribe, unless you tell it not to. This is necessary for some phones for MWI to work. So if you don’t want Asterisk to do this, then you can set the subscribemwi=yes option in sip.conf. This tells Asterisk to only send MWI if there is an associated subscription.

This can help to prevent the WARNING “Remote host can’t match request NOTIFY”. If you want to find out which device is causing this message you need to be quick and enter a “SIP SHOW CHANNELS” on the CLI right after the error appeard, then match the on the call ID and you have identified the culprit. Alternatively you could do a full scale “SIP SET DEBUG” and monitor that long enough.
But of course you could also simply remove the corresponding “mailbox=” line. 😉

Related issues

• 12828: Workaround is/was to set qualify=no (2008)
• 6390: SIP ERROR 481 Call leg does not exist (2006)

See also

• buggymwi for certain Cisco phones
• RFC3261