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Calling Line Identity

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The following details can be configured in the Calling Line Identity section of the carrier settings page.  It defines whether a CLI should be sent to the carrier and the format of that CLI.

 

Enable CLI

Clicking this box will cause a Calling Party Number to be sent to the carrier.  By default, the number sent is the calling party number of user ID of the caller.  But, this can be overridden with the remaining settings in this section.

Default CLI

If an account is not configured to send CLI, then calls to this carrier will be marked as "CLI withheld" unless a number is entered into this box.  In that case, this number will be used as the CLI.

Digits to strip

The number of digits to strip from the beginning of the caller's calling party number before passing it to the carrier as a CLI.

Digits to insert

A digit string to add to the beginning of the caller's calling party number before sending it to the carrier as a CLI.

Type of Number

For H.323 carriers only, you should select the Type Of Number parameter to be included in the Q.931 Calling Party Number Information Element.

 

CLI may also need to be enabled on the originating accounts for these settings to have any effect.

 

CLI format

 

It can be useful to know the means by which a CLI is passed to a carrier.  This depends on the signalling protocol in use:

 

•For SIP carriers, the CLI is passed as the user ID portion of the From header of an INVITE message.
•For H.323 carriers, the CLI is sent in a Q.931 Calling Party Number information element.

 

Authentication issues with CLI

 

There may be calling difficulties if CLI is enabled on carriers that use Asterisk switches or derivatives.  Asterisk uses the user ID portion of the From header for initial endpoint identification, before optionally challenging a caller for further authentication.  Authentication is achieved through separate headers, but, if the user ID in an INVITE message is set to a CLI rather than the authentication user name, an Asterisk server may ignore a call request and not challenge a call for authentication.  For this reason, CLI does not usually work with Asterisk.

 

This is not an issue with normal SIP carriers (carriers that do not use Asterisk).