Calling Line Identification (CLI)

When a a call is made, its recipient is typically presented with some indication of who the caller is, via a short piece of identifying information that appears on their device or app, known as the Calling Line Identification, or CLI.

In most cases, the CLI will be the number of the device used to make the call, but in certain cases a caller may choose to mask or hide their number, or a service may be configured to alter the CLI to something relevant to the answering operator.

Network operators are obliged to ensure their calls meet standards set by regulators and the law. In a police investigation, calls must account for their source, even if this information was withheld from the call recipient for privacy reasons. Because of this, all calls have a Network CLI, which is different from the regular, Presentation CLI.

The network CLI may be captured regardless of whether the presentation CLI was withheld; however, due to the number of options available for controlling CLI, there are circumstances where a call may be left without a network CLI, including:

  • The service is set to display the dialled number, but that number is something that cannot be used as a CLI, such as a premium number.
  • The service is set to display the dialled number, but the call was initiated by an e-mail.
  • The service is set to display the phone number of the first person in the call to the second person, but the first person is using a VoIP phone.
  • The caller is from a different country and is not providing any CLI information.

In situations like this, you can configure the service to inherit a network CLI according to certain criteria. Nobody on the call will be aware of this derived network CLI, but it will be held on record to fulfil legal obligations.

It is the customer's responsibility to ensure that their services provide sufficient, appropriate CLI information to all of their call participants. Contact Support if you have any questions on this subject.