Sip notify MWI

I’m trying to run an asterisk command to turn on/off a message waiting indicator. I saw online a referance to using "sip notify mwi=[yes/no] [peer]"
I’ve attempted this but it kicks back an error that “sip_notify.conf” is missing.

Why is sip_notify.conf missing from freepbx? Does anyone have a copy of sip_notify.conf that would work? Is there a better way to turn on/off a mwi?