What is the proper way to actively subscribe the MWI of a (PJSIP) trunk, given the SIP server of the trunk provider does not send any unsolicited NOTIFY messages
(As far as I understand in chan_sip this can be achieved by adding sth. like
mwi => user[:secret[:authuser]]@host[:port]/mailbox
I use FreePBX 15.0.11/Asterisk 16.3.0.