I have a combination of SPA 502 and 504g sets with a UC320. We are seeing that it can take up to 60 seconds (sometimes more) before the MWI indicator turns on after a voice message is left for a user / phone. And that it will take just as long for it to turn off when the new message is retrieved. Do the SPA 50x phones use a SIP Notify for the MWI or are they using another method. Not sure what the best way to trouble shoot this is?
This is the expected behavior. When a message is deposited there is a minimal amount of post processing that takes place after the depositor disconnects, it is when that is complete that the MWI lamp is lit. Any earlier and the user wouldn't be able to retrieve the message. When a message is deleted, the MWI lamp is not turned off until after the user has disconnected from the voicemail system. Yes, the system is using SIP for the MWI notifications.
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