will having a sip trunk per DID work for outbound caller-id?

[dandenson]

Ok, so I have a customer that requires different caller ids for different departments. I know there is a feature request in for explicit support, but i need this now.

so, will the following configuration actually work properly:
(trunk provider is bandwidth.com)

Every DID gets it's own trunk.
Outbound routes use extension groups and select the matching trunk. This way that trunk's primary number is the caller-id and I have the feature I need.

The question is, with lets say 20 trunks on the system, how does 3CX handle the inbound calls? I'm currently disabling call source identification so I can accept calls from multiple sources on one trunk.

What I'm concerned about is the first trunk will deny the inbound calls because the DID isn't on there and the provider will retry, hitting each trunk down the line until it matches... except they are only going to retry a few times.

Putting all DIDs on the first trunk to avoid this makes for an extremely ugly and basically unmanageable inbound routing because of all the duplicate numbers.

This site is live, I don't want to do a lot of experimenting to figure this out in production.

 

[Saqqara]

Just to clarify the current setup - you have one sip trunk configured and associated with the trunk are the DDI numbers ?

If this is the case, then on each department extension you add the correct DDI number to 'Outbound Caller ID' field. This will only work if bandwidth.com allows you to specify the outgoing number as one of the DDI numbers and not use the main number - you would have to confirm this with them.

You will also have to change the outbound parameters on the sip trunk.

 

[Clément Rousseau]

I dont know if it change depending on trunk provider but for us disabling call source identification is not a problem. Its usually your trunk provider who assign DIDs to trunks, not you. Then I dont see any problem in what you want to try.

 

[dandenson]

Saqqara, correct, currently 1 SIP trunk with all DIDs in it.

current/default 'Remote Party ID - Calling Party : User Part' is already set to 'OutboundCallerId taken from Extension settings'.
For display name, what's the use of that? I can't specify CNAME in the trunk and I believe that's what passing that would do.. am I wrong on that?

 

[dandenson]

@Clément Rousseau I disable call source identification so I don't have to have multiple identically configured trunks for bandwidth.com's redundant SIP server.

 

[leejor]

You are sort mixing an analogue analogy of trunking with VoIP. If people purchase a block of DID numbers from a provider, then they will usually have one trunk group for incoming calls, for those number. The DID information is sent no mater which "channel" on the trunk is used. Again, analogue references to try to explain VoIP..3CX looks at the DID information, in the same way it looks at caller ID (a field of data), then using the DID rules you create, sends the call to the correct extension. With your trunk service, you will be assigned so many concurrent calls. It's not really a channel as such, or an individual trunk as such, it is simply a limit , on the number of calls, placed from at one end or the other, and of course the limitation of the bandwidth to the site. When a DID extension places an outgoing call, you can set the external caller ID against the extension.. That number will be sent on any outbound trunk group, if it is supported by the provider of that trunk, and the options on the trunk are set to allow this. The call does not have to go out on the same trunk group that the incoming DID calls come in on., but they can, and many times do.

 

[3CXEngineer]

As you correctly suggest this feature request is in, you need to vote it up.

However, in the interim, we as a Wholesale SIP Trunking provider can provide you the ability to manipulate the CLI on the fly, so if you have a user, that makes calls for different departments, and you want to present a unique CLI for each department, we can allow this on our SIP Trunks using our gateway. Each call is prepended with a dial code, and depending on the pre-fix code changes the CLI we will present with the call.

We have lots of 3CX partners using this.

Contact me for more information.

 

[YiannisH_3CX]

Hi @dandenson

You can separate your trunk into one trunk per DID to be able to manipulate your outbound caller ID since bandwidth.com is an IP based provider.

On inbound calls the PBX checks all trunks for a match not just the first. So if you set your trunks up correctly you will not have any issues as long as there is only one DID per trunk and your DIDs match the format the provider is using to send the call to the PBX.
I believe bandwidth uses the E164 format (+1234567890) so your DIDs must be the same format.