Consultation on the Calling Line Identification guidelines

The Calling Line Identification (CLI) guidelines aim to help phone companies comply with our requirements that information carried with a call, and the numbers displayed to people receiving them, must be valid, dialable and uniquely identify the caller.

All calls, as a minimum, must have what is known as a ‘Network Number’, which identifies the origin of the call. Traditionally geographic numbers, beginning 01 or 02, have been used as network numbers.  But, in recent years, some calls have begun to use other types of numbers, particularly where these calls originate from VoIP platforms.

We are proposing to further clarify that any valid number can be used as a network number, provided it doesn’t breach Ofcom’s Numbering Plan restrictions, and it doesn’t connect to a premium rate service or revenue-sharing number that generates an excessive or unexpected call charge. Phone providers must also continue to provide accurate caller location information to the emergency services.

Update 16 April 2020 – Deferred final statement

Since the publication of this consultation on the proposed changes to the CLI guidelines, stakeholders have raised a number of additional queries that may require a further consultation on the CLI guidelines. We therefore plan on deferring the final statement on the changes until we have appropriately considered and consulted on the other issues raised. In the meantime, the consultation has shown that some providers already use non-geographic numbers as Network Numbers in some calls. The CLI guidelines at present do not expressly preclude the use of non-geographic numbers as Network Numbers, as long as the number that is provided also complies with the other requirements of Network Numbers.