Calling line identity meaning

Calling line identity (CLI), also called calling line identification or caller ID, is the facility that presents the telephone number of the line from which a call originates to the called party and/or to communications providers. The term is used across telecoms, privacy and marketing compliance, and is referenced in legislation and regulatory guidance (including the UK Privacy and Electronic Communications Regulations 2003 (PECR), Ireland’s ePrivacy Regulations, and Ofcom/ComReg rules). Key legal features and uses: - Identification and tracing of calls (including nuisance and scam calls), often relied on in investigations, evidence and disclosure. - Regulatory obligations on communications providers to offer accurate CLI facilities and, for certain calls (notably direct marketing), to present a valid, returnable number rather than conceal identity. - Treatment as traffic data and, where it identifies an individual, personal data under UK GDPR/GDPR, engaging data-protection requirements for collection, presentation, withholding and retention. - Caller options to withhold or restrict presentation, subject to statutory exceptions and regulator controls; risks include CLI “spoofing”, which regulators seek to deter. Usage and regulatory approach are broadly consistent across England & Wales, Scotland, Northern Ireland and Ireland, with detailed guidance issued by Ofcom (UK) and ComReg (Ireland).