489 4xx Client error RFC 6665
SIP 489 Bad Event
The server does not understand the event package in a SUBSCRIBE or NOTIFY.
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Common causes
- BLF, presence or message-waiting subscription to a server that doesn't support that event.
How to fix it
- Disable unsupported subscriptions on the phone, or enable the event package (presence, dialog, message-summary) on the server.
Seeing 489 on calls through a router or firewall? Check that SIP ALG is disabled. It causes a surprising number of SIP errors. Read why.
About 4xx responses
The request has a problem or cannot be completed at this server, usually because of something on the requesting side or the target user.