Shared Line Appearance

[gregitx]

A bit spoilt after using a Linksys SPA900 but with it I can assign an extension as a shared line with the ability to set that as a line on each phone. IE SPA941
When a call comes in all phones will ring and anyone can answer but when put on hold it can be picked up from any other phone instead of having to transfer.

Just a nice feature if you are in the office alone and want to take a call on another phone, you can put on hold and then move to other phone and pickup

[itfarmer]

I think they introduced something like that.

Forgot how they call it, but it allows you to answer any ringing phone from any extension.

I guess you can, instead putting the call on hold, forward to the extension you going to pick the phone up from.

But that is not the same is it?

[gregitx]

Hi Itfarmer

The nice thing about shared line appearance is that you can see which line is being used just by looking at the phone

The SPA9000 is a good system but just limited in it's expandability ie: 16 phones max / 4 lines max

[miloabc]

I think this would be a very useful feature for the 3CX system to have.

[archie]

Shared line is introduced in V4A. It couldn't to pickup call-on-hold though, but you can use park/retrieve functions to do that. Which are also introduced in V4A

[kustura]

But, how would that shared line feature work? I have a customer who likes the analog phone system's ability to see all line and extension lights on the phone itself. That way, he can tell if someone is on the phone or DND, or if a line is on hold for a long period of time.

[archie]

That feature you're asking for is not shared line, it is BLF, as far as I know. And we'll provide that feature quite soon. Actually, it is almost done.

[kustura]

What is BLF? Are you saying you will be able to display line and extension status on the hardware phones?

[archie]

Yes. It is already working for Snom phones. Still doesn't work for Grandstream (by some unknown reason). Will be available in beta.

[BJReplay]

What about BLF / Share Line Appearance for SPA941 (and similar)?

Planned for V4?

[archie]

What mechanism of BLF SPA is using? "dialog-info" or "presence"?

[BJReplay]

What mechanism of BLF SPA is using? "dialog-info" or "presence"?

Here's from the manual: The 900 Series phone supports shared call appearances in association with a Broadsoft application server. An extension can be shared by two or more stations. All call appearances on a shared extension are shared. At any given time, each station sharing a call appearance can monitor the state of the call appearance. A station can select a share call appearance to make a call only if the call appearance is not being used by another station. All stations ring on an inbound call to the shared call appearance extension. Whoever picks up the call first takes the call. When a call is placed on hold by one station, it can be resumed from another station sharing the same call appearance.

That doesn't help you, of course, but if you can suggest how I can determine this using some sort of logging tool, then I'm willing to try.

[archie]

No, we do not support proprietary protocols like mentioned Broadsoft.
But, we have solution for you. Since version 4 we've implemented 'forked id' feature, which could be used as a shared line. You are not required to do any additional settings, just set up two (or more) phones to use the same extension number. After they are registered - they all will ring on incoming calls. It is also possible to monitor state of the line (shared extension number) using "dialog" event (since V4) or "presence" event (coming really soon). So, combinig these two features you can achieve SLA behavior on almost any phone (in full, or partially depending on phones ability to subscribe for beforementioned events).

[BJReplay]

Since version 4 we've implemented 'forked id' feature

Thanks, I'll try that and see how it works...

I've got tracing for the SPA-941 on reboot (IP Addresses and DNS Names changed to protect the guilty )

First, without Shared Line Appearance (normal)

Code: Select all

REGISTER sip:my.3cx.server.address SIP/2.0
Via: SIP/2.0/UDP my.client.ip.address:5070;branch=z9hG4bK-65104994
Max-Forwards: 70
Contact: "ExtenstionName"<sip:109@my.client.ip.address:5070>;expires=240
To: "ExtenstionName" <sip:109@my.3cx.server.address>
From: "ExtenstionName" <sip:109@my.3cx.server.address>;tag=ff7897d92d8155f2o0
Call-ID: 38b1552d-6925990a@192.168.1.155
CSeq: 24659 REGISTER
Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER
Supported: replaces
User-Agent: Linksys/SPA941-5.1.8
Content-Length: 0

Then with Shared Line Appearance

Code: Select all

REGISTER sip:my.3cx.server.address SIP/2.0
Via: SIP/2.0/UDP my.client.ip.address:5073;branch=z9hG4bK-768fe840
Max-Forwards: 70
Contact: "ExtenstionName"<sip:SharedLineID@my.client.ip.address:5073>;expires=240
To: "ExtenstionName" <sip:SharedLineID@my.3cx.server.address>
From: "ExtenstionName" <sip:108@my.3cx.server.address>;tag=162563b1510b3bfao3
Call-ID: 1718ecfa-ecf39ba1@192.168.1.155
CSeq: 59047 REGISTER
Allow: ACK, BYE, CANCEL, INFO, INVITE, NOTIFY, OPTIONS, REFER
Supported: replaces
User-Agent: Linksys/SPA941-5.1.8
Content-Length: 0

The key difference is the SharedLineID (which is what I put in the SPA-941's field for SharedUserID is substitued in place of the UserID in the register for the Contact and To fields, but not for the From Field.

And a second or two later, a SUBSCRIBE for Call Info events - so I think this is the crucial event it's after to indicate the status of the line.

Code: Select all

SUBSCRIBE sip:108@my.3cx.server.address SIP/2.0
Via: SIP/2.0/UDP my.client.ip.address:5073;branch=z9hG4bK-dcf30be8
Max-Forwards: 70
Contact: "ExtenstionName"<sip:SharedLineID@my.client.ip.address:5073>
To: "ExtenstionName" <sip:SharedLineID@my.3cx.server.address>
From: "ExtenstionName" <sip:108@my.3cx.server.address>;tag=20f8b39cdebcb596
Call-ID: af749894-c0d54fe@192.168.1.155
CSeq: 55501 SUBSCRIBE
Expires: 3600
User-Agent: Linksys/SPA941-5.1.8
Event: call-info
Content-Length: 0

I don't have a SPA9000 to find out what would be sent by one of these, but this might help you support this (popular phone).

[archie]

This "call-info" event is not standardized by IANA (there's no RFC on it), so it is proprietary extension by Broadsoft. And we're tending to support only standard SIP features.
But I have found Broadsoft's documentation on it and am going to investigate this question deeper. No promises, but if we found it worthwhile - we could implement it.