Odd question about PJSIP, Consolidated MWI and BLF

This may seem a little odd, but follow me here. Grandstream phones - the BLFs, have the ability to subscribe to a BLF Event List as well as individual subscriptions. Lets take an operator console/switchboard as an example. Has a ton of sidecars/button modules. Lets say she’s got 100 BLF subscriptions. In the normal world, those all have to be subscribed to individually, and each status change is a single message.

I noticed, in PJSIP, there’s an option to AGGREGATE MWI, which (in theory) takes multiple MWI subscriptions and consolidates them into a single NOTIFY for the phone. Is there any way to do that for BLF?

On Grandstream, you build the BLF Event List in the system, then on the phone you build the button as:
BLF Event List (Extension in the list you want to monitor).

So, basically, the phone is looking for the status update within the long notify with all the event list members, rather than just a stand-alone notify.

PJSIP’s Aggregate MWI made me think that could possibly be used for BLFs as well.

Not sure if I described this well, but it was just a thought. Trying to cut down on traffic and missed BLF status updates on a deployment we have (like 60 phones, with over 40 BLFs on each phone - sigh).


No one has any thoughts/comments on this?

This is something I have only just recently heard about, and some quick googling got me to this page:

Based on the above link, we can see that GrandStream EventList buttons comply with SIP standard RFC 4462. From some basic research, I can see that Asterisk does indeed support RFC 4462 in what it calls Resource List Subscriptions (RLS):

Support for RLS is quite new in Asterisk, introduced in ver. 13 and only for PJSIP extensions. Unfortunately, there is absolutely nothing in FreePBX at present to support this feature but there is an open feature request here which you can watch for auto progress updates:


Hi Lorne,

Thanks for the info, by following the info, my GXP2170 successfully populated RLS list. :slight_smile:

Below is what I did, just for my record.

  1. Created RLS list under /etc/asterisk/pjsip_custom.conf

    type = resource_list
    event = dialog
    list_item = 1000
    list_item = 1001
    list_item = 1010
    notification_batch_interval = 3000
  2. Open Web GUI page and configure Account 1 (ACCOUNTS → Account1 → SIP Settings → Advanced Features)

  3. Add created context name in Eventlist BLF URL.


  4. Adjust VPK so that list of RLS will be shown up from VPK #4 position. (SETTINGS → Programmable Keys → Virtual Multi-Purpose Keys)
    This is for my setting, since my user does not require more than 3 concurrent calls, and I dedicate just 1 account for the phone. At least 3 lines should be available for 3 way quick conf. call…

This is quite nifty, since manual configuration of VPK for this phone is quite cumbersome. I also noticed firmware tends to maintain IP address given by DHCP server (so that it will use the same IP address even the phone is restarted. In previous version, the IP address was keep incrementing which was a bit annoying when the phone was in debug phase)

Software version:

  • GXP2170 firmware version:
  • Asterisk version: 13.23.1
  • FreePBX version:

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