Strange SIP NOTIFY behavior

We see the same behavior… very high network load which appears some time after a APPLY in the GUI.

Is there any way to bulk update all extensions to set MWI Subscription Type to “Solicited”?

Can we set it by default to Solicited when creating a new PJSIP extension?

Final question: Does this setting have any impact on BLF? Or is it just used for voicemail notifies?