Passing data in custom SIP headers

[NicholasBarnes]

We have our own interconnects, multiple wholesalers and have written our own billing platform - all our and our customers' 3CX boxes create SIP trunks back to our SIP routers. Everything is under our control.

Our billing system is capable of using custom SIP headers to allow billing to be totaled for sub-accounts (e.g. customer A wants their bill to be split into totals for Sales, Support, Accounts...). With our non-3CX PBXs, we just define a custom SIP header (say "X-Billing-SubAccount: Sales") and the SIP router directs the billing platform to use this to produce departmental itemisations and CDRs.

We also have a need to pass other information in SIP headers, but this is the most pressing.

I've gone through the options and it seems the only way I can do this is to create separate SIP trunks for each sub-account and then alter the outbound headers for that trunk. As the customer we need this for has around sixty departments and has the ability to create them dynamically, this isn't an option.

Is there any other way I can get a user's details, extension, group or anything like that into a SIP header? If not, is there any other way of getting this information out of 3CX when a call is made?

I'm fully expecting the answer to be "No, you can't do that", but I thought I'd ask just in case I missed something.

 

[cobaltit]

The only think I can think of is if you modify the trunk settings to use one of the RPID or P-Asserted fields to use the callerid from extension and assuming you don't currently use that for CID nor do you use the extension level caller-id. I don't think any checking is done as to the data in that field

 

[YiannisH_3CX]

The PBX will not send an extension number through a SIP Trunk for security reasons unless its set as the outbound caller ID of the extension.
With that in mind I will say "No, you can't do that". All the available options are under the outbound parameters of the trunk settings. We do not have an option for custom SIP headers.

 

[NicholasBarnes]

use one of the RPID or P-Asserted fields to use the callerid from extension and assuming you don't currently use that for CID nor do you use the extension level caller-id.

I have had a play with that. I can get the extension's user name (e.g.
"P-Preferred-Identity: "Nicholas Barnes"<sip:anonymous>"), but I can't get the extension number out of any of the available options (despite there being no extension level caller-id, the user ID field is always set to the external CID number). :-(

 

[NicholasBarnes]

The PBX will not send an extension number through a SIP Trunk for security reasons

There are, in my case, no valid security reasons for this.

 

[cobaltit]

If the extension level CID is not being used, you could use that field to pass along anything you want (extension number, group name, etc) in one of those fields and then let the trunk level CID take over for the actual CID>