Yes they are. That’s is what I get for not checking more carefully on an unfamiliar system.
192.168.201.150 is the PBX.
So now the question is why is anything being sent to 64 at all when it does not even have a voicemail box for a MWI indicator to be subscribed to in any form.
Edit: Everything is set mwi_subscription = auto and aggregate_mwi = no by default.
mwi_subscription options are auto, solicited, and unsolicited. I have now set everything to Solicited and we shall see how it goes.
OP and title updated to match.
Reference: Strange SIP NOTIFY behavior