Subscribe MWI notifications from TRUNK on PJSIP channel

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
to sip.conf.)

I use FreePBX 15.0.11/Asterisk 16.3.0.

PJSIP does not support receiving normal MWI notifications or subscribing for them.

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I don’t have a solution, but what you are asking seems very unusual.

When the PBX is working, you would normally want it to handle all voicemail (multiple mailboxes, better notifications, etc.)

If the PBX is down or for some reason is unreachable and the trunking provider takes a voicemail (failover mechanism), attempting to notify the PBX wouldn’t help. In any case, this should be an urgent notification as you may not know that it’s down. Can your provider send an SMS or push, or at least an email, when they take a ‘failover’ voicemail?

That is, of course, assuming this is failover. The amount of people that put their PBX on standard VoIP services (aka meant for ATAs, IP Phones and follows traditional phone service) and then have issues with the calls rolling over to voicemail due to NAT issues or whatever.

A SIP Trunk provider isn’t going to have voicemail as part of the normal services. They are there to provide origination/termination services only. Subscriber level services are left to the subscriber (aka the owner of the PBX). Their failover options would be to send the call to another SIP URI or to a phone number over the PSTN.

@hobbit378 What kind of service is actually being given by the provider? Is this a SIP Trunk service meant for PBXes or is this just some SIP/VoIP line service and you’re putting a PBX on it?

Indeed this is meant as a mere additional failover solution for calls coming in when my FreePBX is temporarily down/unreachable for some reason with incoming voicemail then instead being received by and stored directly in the voicemail box at the SIP provider.

(@Blaze Studios: I have subscriptions with several SIP Providers for (mere) SIP/VoIP line service (including also a voicemail box) which I have connected to my FreePBX)

Of course, (most of) those voicemail services can be configured to send an email notification in case of an incoming voicemail. Yet, I thought it would also be a nice idea to have an additional reminder in form of a flashing MWI LED once my own FreePBX is up and running again.

I have subscriptions with several SIP Providers for (mere) SIP/VoIP line service (including also a voicemail box) which I have connected to my FreePBX

Thanks for your reply, yet what slightly puzzles me about your answer is that the pjsip stack appears to contains an API for supporting the SIP MWI Extension (including API calls ‘pjsip_mwi_create_uac’ and ‘pjsip_mwi_create_uas’ for “Creating MWI client/server subscription session” , c.f. ).

Could you elaborate a bit further what you mean by ‘normal’ MWI notifications, thus are there different types of it, or differences in the way they are handled by chan_sip and chan_pjsip respectively?

Asterisk provides a mechanism to exchange MWI between instances using its own payload, that is what I was referring to.

And yes, while PJSIP may have an API for doing such a thing the functionality still has to be written to use it and configure it. Noone has done that.

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