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  • Written by Tom Snee
NICC, the UK’s technical forum for telecommunications, has published its updated specification for the ‘Requirements on communication providers in relation to CLI (Customer Line Identification) display services and other related services’.

This NICC document, ND1016, outlines the principles for the use of CLI and includes reference to the Ofcom CLI Guidelines which state the requirements on UK communications providers for the provision of features that utilise CLI information.

The purpose of ND1016
The underlying purpose of ND1016 is to provide detailed technical specifications for how CLI data is used and transposed, particularly when calls are passed between networks. In particular, it covers communications providers’ responsibilities in relation to:

  • the origination of customer line identity information
  • the transmission across networks of such information
  • the delivery to a network termination point of customer line identity information or the reason for its absence

Updating and improving the ND1016 specifications
In 2013, in the context of its work to trace nuisance calls more effectively, Ofcom asked the NICC to review ND1016. In particular, Ofcom wanted to ensure the specifications kept pace with any relevant technological advancements.

NICC reviewed each of the rules specified in ND1016 to ensure that they remained relevant, were technology neutral and, where necessary, began developing new specifications as to how information from one network protocol standard should be transposed into another, to minimise data loss or corruption.

Adhering to these updated specifications should better assist communication providers in following Ofcom’s CLI Guidelines and therefore help them meet their statutory obligations under the relevant regulations and legislation.

The updates should also lead to fewer instances of missing or mal-formed CLI being sent through the networks and presented to consumers, and, in turn, allow recipients to make more informed choices as to whether or not to pick up an unrecognised incoming call.

Additionally, the changes should also help Ofcom trace nuisance calls through networks to their source (as per ND1437) more effectively, as more accurate and consistent call information should be available more frequently. Also, UK-agreement regarding CLI signalling and consistency can help in efforts to promote a common approach internationally so that CLI is less likely to be erroneously discarded as calls traverse international networks and hence give consumers further confidence in CLI.

Huw Saunders, Ofcom’s Director of Network Infrastructure, commented: “We consider the NICC’s revisions to current rules on how CLIs are passed between networks and presented to customers to be crucial to our work in tackling the issue of nuisance calls.

“We hope to capitalise on the clearer, more consistent and accurate call information that we expect the new specifications to provide, as we work to trace those responsible for targeting consumers with unsolicited calls. The NICC’s expertise will continue to be invaluable as we work together to ensure communications providers adhere to the new specifications and that they are operating effectively.”

ND1016 also provides guidance to Customer Premises Equipment (CPE) manufacturers wishing to implement automatic call rejection equipment based upon CLI. The Ofcom Guidelines for anonymous call rejection assert that where CLI information is displayed prior to the call being answered, end-users must be able to reject incoming calls.

CPE manufacturers are required to relay an announcement to inform the caller that their call has been rejected because they restricted their CLI. This gives the opportunity for the caller to redial the number without restricting their CLI. This feature is important as many organisations such as hospitals, police and GP surgeries restrict their CLI routinely, but it could be vital that they are able to speak to someone whose line has the anonymous call rejection service.

Among other presentations, ND1016 will be discussed at this year’s NICC Annual Open Forum (for the draft program) at 1 Great George Street on 12 November 2014. The conference in Westminster will provide networking opportunities and insight on developments within the telecommunications industry. To attend the event, please email NICC secretary Nick Ireland at

For more information about NICC, please go to