Display Callee Status on Caller Phone


I deployed Asterisk/FreePBX in our organization last week. More than 130,000 calls answered in that time… pretty good, I think.

Our users started looking for a feature that existed on our old system as soon as the new system went online: the old phone system would light up an icon on the phone’s display if the extension being called was busy. Apparently this is a very important feature internally… users will typically end a call to another extension as soon as they see that the person they are calling is on the phone. Without such an alert, callers have to wait for the phone to ring to voicemail to find out if the callee is away or just busy.

Under “Dialplan and Operational” in “Advanced Settings” I see a setting for “Display Presence State of Callee” - the help tip says this…

[color=#0000FF]When set to true and when CONNECTEDLINE() capabilities are configured and supported by your handset, the name displayed will include the presence state of the callee.
Default Value: True

… I have it set to true, and that’s as far as I’ve gotten.

Does anyone have any suggestions for getting this feature to work, or where to start looking to figure out why it is not working?

Thanks in advance!


This is called busy lamp field. You will have to ask on freepbx.org/forums/ to see if FreePBX supports it.

I don’t think BLF is what I’m looking for… not from what I’ve found from some searching so far. BLF lets you program a button on the phone to monitor an extension. That’s not what I’m looking to do here. I’m looking to use the ConnectedLine() feature of Asterisk as described to alert a caller that their callee is currently on a call.

BLF (Busy Lamp Field)
The Busy Lamp Field (BLF) feature allows you to program a key that monitors
whether or not another user is on a call.
The BLF Key also acts as a Speed Dial key to the monitored user’s number, and as a Call
Pickup key on behalf of the monitored user.

There should be no delay between detecting busy and the initial voicemail announcement, so they should not need to wait.

Plain Asterisk can do an arbitrary voice announcement before going to voice mail. You could also use the REDIRECTING feature, but that would need support from the phones. You could also abuse CONNECTEDLINE, again assuming support from the phones.

You may be able to use presence features using a dummy device state to represent the state of the callee of the current phone, but you would have to be careful that you didn’t fail to clear it down when they hung up. This would require BLF type support in the phone.

You could send a message or a URL to the phone, but that assumes support in the phone.

However, you are not using plain Asterisk, so you will be constrained by FreePBX, and will need to ask on the forum I already mentioned.