Maximum concurrent lines for SIP extension


how many maximum concurrent lines are available for a SIP extension?
Is it somehow possible to use e.g. 4 lines for one SIP extension at the same time? If so, how can this be achieved, only if I place three other on hold, or is it somehow possible to put out the stream on different devices, e.g. if I have a suitable SIP Client on my PC?

Thank you

many times, this is phone dependent.
There is a limitation of your phone! You can set limits per extension in FreePBX as well. Say, for example, conferencing. Technical when you conference a line, in the traditional days, the conference happened at the PBX, in VoIP, asterisk anyway, it happens on the phone.
Multi line voip phones can have multiple appearances of the same number, so if you are on a call and someone else calls you, instead of it going directly to VM, it might ring one or more of the additional lines on your phone.

Thank you very much for your quick reply.
So that means, if I have the right phone, or phone software I can even have 2 or more callers on the line at the same time, right? Do you know a SIP Client software which can do this?

XLITE supports it, I think it can do at least 2 calls simultaneously.
In that program you see 1 line, each subsequent call appears in the xlite window for you to have the option to answer it.
I’ve got a bunch of Nortel 1100 series phone, and it shows 1 line, but each calls appears on the LCD screen. My polycoms show multiple lines with the same number, and you can have multiple calls all going, just select the line you want to talk to, or you can CONF them all together into a single line.

I don’t understand whether you want to talk to multiple people at the same time (a conference call), or juggle multiple concurrent calls from unrelated customers, speaking to one at a time.

For the former, all IP phones (and some softphones) allow 3-way calling (you and two external parties). High end phones can support more, e.g. up to 5 for Sangoma and 6 for some Polycom phones. You can also use the conference feature built into FreePBX, or an external free or paid conference service.

For the latter, all IP phones support ‘call waiting’ with two external calls; some support more. But in my experience, juggling more than two calls provides a poor experience for the customer and you should use a queue instead.


ok if I use e.g. zoiper I can see that I can have 4 inbound calls which are listed, I can have one active and the others are on hold or are ringing. Does anyone know a free Softphone, which is capable of creating a conference with more than 3 users? I tried X-Lite, but with X-Lite only a 3 way conference is possible.

@dickson: so you can also have a 6 way conference with your polycom phone, because you make more than one line and all lines with the same user and authentication to freepbx?

The conference activity occurs on the phone, so its a limitation of the phone hardware that limits the conferencing ability. But essentially yes, you can have multiple lines and they can all share the same extension information. Again,phone specific, but essentially there is a “Number of appearances=X” value in the phone config.

If you want to do more conferences, you could consider just using asterisk “conference system”. You could transfer users to the bridge, you can have al ot more people that way.

For clarity and completeness, the maximum number of concurrent channels for each sip trunk (not extension) is determined by your VoIP provider.

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