One SIP, many outbound numbers config in FreePBX

Hi all,

I have a SIP trunk that contains 10 numbers. So my question is how can I config that trunk to auto-select any available number for outgoing in FreePBX. I mean think one employee dialled on xx number. So another employee should be able to call out on yy number. How can I config this in FreePBX or is it possible?

Thanks in advance.

Why do you feel like you need to do this? Dialing out on SIP doesn’t require you to use a different outbound DID if there is a call that was already made and is in progress on one. Every call can have the same outbound DID.

Dialling analogue, or ISDN, doesn’t require that each circuit have a distinct caller ID (DID only applies incoming). This has been very standard for business lines for at least half a century, and probably a lot more. This isn’t something that is new to SIP; it is something associated with any business using a PBX, as against a key and lamp system or individual lines.

I am sorry, I am dense and am not getting this clarification.

He said he was using a SIP trunk and I didn’t want to assume so I asked for clarification as to why he felt he needed to use a different outbound DID if somebody had already dialed out on the, let’s call it, first DID available in his pool of DIDs.

I am not saying there isn’t a legit use case but I haven’t encountered it yet and I am just trying to understand what it is. I also wanted to make sure that the OP understands that in the SIP world you don’t need to do this as the call will still go through even if you used a DID that’s currently being “used”.

I’m not disagreeing that it would be strange for a SIP service aimed at PABXes to limit calls to one per caller ID. What I’m saying is that this strangeness isn’t something new to SIP, it is how business numbers have worked for many decades, from long before the internet.

I’m also challenging a further extension of the misuse of “DID” in the VoIP world.

Historically, a business might have had dozens of lines in a a hunt group, all of which had the same directory number and presented the same caller ID. The term DID was never applied to such a directory number; it was just the phone number of the PABX.

With real direct in dialling (in many cases DIDs are only direct in dialling to the provider, not to the customer), you might have, say 50 lines and a block of 1,000 numbers, if you were a big user. Incoming calls on any of those 1,000 numbers would hunt over the 50 lines. Outgoing calls, in the early days, would also hunt over the 50 lines, and would present a pilot number, normally the first in the range of numbers, although ISDN made it possible to present other numbers, and many big users chose to not present one at all, as they couldn’t tell where to send returned calls.

With SIP, what you sometimes get is accounts with a limit of one simultaneous call, but it is the account, not the directory number that has that limit. Such accounts are not intended for PABXes, but for single phones.

It is possible that, if you try to use multiple such accounts with FreePBX, FreePBX has difficulty telling them apart, so they look like one trunk, rather than a trunk per account, which is maybe what is happening here.


Hi all,

Thanks all for your replies.

So each and every time outgoing call will go through one number until my sessions are full. Incoming calls from all 10 numbers can be directed to any extension number configured.

Just think a company Director or someone like that called an outside person from his extension, he wants to go that call through a separate number and it is in the number pool of the SIP trunk.

After reading the replies from you guys, might seem like it is not possible to config.

For each user that has a personal number that rings to their extension, set Outbound CID for the extension to their number, so calls made from that extension will show the correct number to the called party.

For other users, you can set Outbound CID to your main company number, or leave it blank and set the Route CID for the Outbound Route to your main number.

If this isn’t what you want, please explain how the system should know which number to send.

Hi @Stewart1 .

Yes, this is what I needed. Can you please tell me where can I set this setting in FreePBX?
Thank you.

Outbound CID is a setting for each extension. If it’s not working, check that you are not overriding it in the Outbound Route or Trunk, and the Trunk settings are as your provider requires.

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