BLF to show if any callers listening to IVR / taking up lines?

With conventional Key phone system, one of my customers is used to having line keys that show status of every line (in use or not), which means that if a caller is listening to an IVR message/office greeting then they’re taking up a line so the line key for that line will show as busy.

The goal is to have a BLF that lights up as in use whenever any trunk is in use no matter how it is in use. i.e. if someone is listening to IVR prompts or recordings or leaving a voicemail etc. then it’s in use so the BLF should light up.
How to do this?


Over the years, I’ve done just what you are asking.
Usually, it is for a heavy-sales (incoming calls) type of operation.

Although, from memory, I don’t recall the exact way we did this, but in general the fix was to:

Setup Ring Groups, and use the Ring Group number as the BLF.
example: as people call in: and they press option 1 for sales (RG 600) … or option 2 for support (RG 601) … you would see the callers move through the system on your phone because all the ring groups involved in the IVR were setup as BLFs on a sidecar attached to the key phones.

Might be more to do than just this, but I do recall we were able to show the incoming calls, and how the caller’s were “moving through” the system tree.

If I recall more, I’ll update things.

You have to keep in mind that with a conventional keyed system, they were connected with POTS/PRI/T1 aka TDM circuits which mean there were individual channels. Individual channels that the system to see if they were either on-hook (not in use) or off-hook (in use). With a keyed system you could say lines 1-4 are inbound and 5-8 are used for outbound. This is pure SIP so you don’t have individual channels, the endpoint (trunk) is either in use or not in use and that could be either an outbound or inbound call. You won’t be able to see if lines 1-4 are in use or not because there are no lines 1-4. Any channel limits or control with SIP are done logically not physically.

I understand that, sorry I probably misworded my original intent as I was used to working on these good ol’ key systems for years…
Not looking to monitor status of lines since I know that doesn’t exist in SIP trunking.

Since client already has BLF keys for all the employees’ extensions, a simple BLF to monitor the status of the whole trunk would be enough. That way if they see no people on the phone and the trunk’s BLF is red then that means some caller is listening to av IVR or leaving a voicemail etc. How to program a BLF that monitors the status of a trunk?