How to show the available and busy lines / busy extensions on phone display?

I am setting up a freePBX to replace an old AGFEO ISDN PBX.
And I am wondering if I can replicate a very neat feature of the old AGFEO Phones.
They show on their display the available and busy external lines.
Very simple like this
means 3 out of six available lines are busy
Below it shows the busy extensions in a row.
Looking like this:
23 56 46 34
Very easy and convenient especially for a pbx with few external lines and a lot of infrequently used extensions.
So far I only read about phones with big sidecars with busy lamp fields, but thats too bulky to use exept on a receptionists desk. But its good to know before dialing if someone or the lines are busy.

Any Ideas ?
I did not jet order phones, so you also might suggest phones that help me in realizing this
Thank you!

Are you still using ISDN?

On a modern system, you don’t have to worry about ‘lines’. Your trunking provider provisions a sufficient number of channels so you can always make an outgoing call, without fear of blocking any incoming calls. An incoming caller should never get a busy signal. Of course, you can still have a problem if you don’t have enough staff to field all the calls coming in; a customer who waits in a queue for 30 minutes may leave for a competitor. There are various options, including giving queued callers the ability to leave a voicemail or request a callback.

You might choose a phone with (for example) 12 line keys such as Polycom VVX 411, setting up the 6 keys on the right as BLF for your most frequent contacts. You see their names and the associated light indicates their status. Touch the button to call them or transfer a call to them. In most situations, there are few internal calls to users without a BLF key, so it’s not a big deal to leave a message if their phone is in use.

Sangoma makes good phones that integrate well with FreePBX, though they are somewhat wider than the VVX. Is that size acceptable?

At the moment we are still using the old ISDN System, connected via al LANCOM R884VA Router that provides up to 4 ISDN Channels converting from VOIP.

Well we have about 70 Extensions and only 6 (VOIP=ISDN) Channels, which were always enough.
And are even more so now as people are also using their mobile.
And more channels would cost more per month, though not much.
Its more an Idea of giving many of us an opportunity to understand whats going on, and with ISDN this was a feature many brands had.
So as I said a BLF doesnt make sense for 70 rather infrequently used extensions (we are not a callcenter) I am really wondering why I seem to loose functionallity with a more modern system.
Arent these values just variables a phone can request from the system ?

You effectively currently have a ‘Key System’ yet FreePBX is essentially a ‘Public Branch eXchange’, Googling the differences will soon show why BLF’s for trunking is not really a ‘thing’ in this Milieu

Please be more precise when giving references. I checked this comparision

and would say “no we dont have a key system”

The KSU connects to telephones, which have multiple buttons that represent individual lines. When you want to make a call, you pick up the receiver and press a button to access a phone line.

We have an Agfeo AS 200 in full extensions configuration with 80 Extensions (Minus 3 used for the external lines) You can Google it :wink:
I would call this a proprietary pbx on special hardware.

And still it matters to me to easyly see how many external trunk channels and which Extension are busy.

Anyone any constructive Ideas instead of talking me out of wanting this?
(I know its not a must have, just a collagues want it feature)

Basic rate ISDN never took off in the UK except for use by the media, often with one end at home, so I’ve never been exposed to actual equipment, but this looks, like it is intended for small businesses, upgrading from key systems, so is trying to emulate them, rather than Private Branch Exchange. In fact, if I understand the S bus concept, they may behave a bit like key system units, in that the extensions share the interconnect wires, and that imposes limits on simultaneous calls.

With FreePBX and IP phones, knowing an extension is busy is done with busy lamp fields. However, unlike ISDN, where there are identifiable circuits (B1 and B2) for basic rate ISDN, VoIP doesn’t have numbered channels that are allocated. The nearest to a channel number is the call ID, but that is unique for every call.

I have heard that some, low end, providers do impose limits on the maximum number of simultaneous calls, but that isn’t by having a fixed number of circuits, but rather by having a maximum count of active calls.

Therefore I think you can monitor your extensions, but channels on VoIP trunks are meaningless, so you cannot monitor them.

I personally would say you have a key system that if from toshiba or whatnot would be called a 6x72 or somesuch, the 6 is for phone-lines the 72 are the stations , phone-lines in PBI are grouped into trunks, and trunks can have 1 to lots of ‘phone-lines’. So having a busy trunk is not the same as having active channels in that trunk but active channels are only enumerated directly by DAHDI channels by Asterisk.

But as you wished

I think the discussion about key system or not is leading nowwhere.
But I will watch that video and see if it helps me.
I like crosstalks videos very much but did not find that one.
Thank you!

Ideed all german providers that are available here and within our cost limit, limit the number of simultaneous calls.
Basically because you pay per this number for the flatrate tarifs.
So it is relevant to know how many external calls are going on.
I would not need to have this matched to any “lines” wich are naturally not existant in this case.
To see a simple Number would be enough.

Thank you for taking your time to help!

The Video from Crosstalk Solution on emulating a line system is interesting and well made.
I really like those videos.

But it covers none of my question, I don’t need the funktionality mentioned there, though I learned a bit about provisioning phones in general.

Anyone with Ideas how to Display the extension numbers of the extensions with an active call and the numbers of active outside calls on a phone display ?
Could be any phone that you can recommend.

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