TPS, CTPS and HLR: Keeping UK Outbound Lists Clean, Compliant and Cheap to Dial

Every UK firm that makes outbound marketing calls is sitting on two separate problems hiding inside one list: a compliance problem and an efficiency problem. Get the first wrong and the fine is now measured in millions. Get the second wrong and you're paying agents to listen to dead lines. TPS, CTPS and HLR screening are the three tools that deal with both — and they're routinely either skipped or done once and quietly forgotten.

TPS and CTPS: the legal bit

The Telephone Preference Service (TPS) is the UK's official opt-out register for individuals who don't want unsolicited live marketing calls. The Corporate TPS (CTPS) is the equivalent for business numbers. Under the Privacy and Electronic Communications Regulations (PECR), making an unsolicited direct-marketing call to a number registered with TPS or CTPS — without that person's specific prior consent — is unlawful. Full stop.

This isn't a grey area, and it isn't advisory. It's enforced by the Information Commissioner's Office (ICO), and the stakes just rose sharply. The Data (Use and Access) Act 2025 raised the maximum penalty for PECR breaches from the old £500,000 cap to £17.5 million, or 4% of global annual turnover — bringing telemarketing breaches into line with UK GDPR. The ICO issued £4.63 million in PECR fines in 2025 alone, and unlawful marketing calls remain a standing enforcement priority. A 35-fold increase in the maximum penalty turns "we'll screen the list eventually" into a board-level risk.

Two things firms get wrong:

• Screening once. The TPS register changes every day — people register all the time. A list scrubbed three months ago is not a compliant list today. Screening has to be recent and repeated, not a one-off at the point of purchase.
• Forgetting CTPS. Plenty of firms screen consumer numbers against TPS and never touch CTPS for the business numbers they're calling. Both registers apply.

The practical answer is automated screening against the live TPS and CTPS registers, run on a schedule, with an audit trail showing exactly what was screened and when — because if the ICO asks, "we think we screened it" is not an answer.

HLR: the efficiency bit

HLR (Home Location Register) lookup is a different tool for a different problem. It isn't about consent — it's about whether the number is even worth dialling. An HLR lookup queries the mobile networks and tells you, for a given mobile number, whether it's live, invalid, disconnected, ported, or unreachable — before your dialler ever calls it.

Why it matters:

• Dead numbers waste money. Every disconnected or invalid number your dialler attempts is dial time, trunk cost, and agent capacity spent on nothing. On a large list, the dead-number percentage is usually higher than firms expect.
• It steadies your dialler. Cleaner lists mean your dialler's pacing decisions are based on real, reachable numbers — which keeps your abandoned-call behaviour more predictable (see our piece on Ofcom and abandoned calls).
• It reduces nuisance to reassigned numbers. Numbers get reassigned. HLR validation helps you stop calling a line that's no longer your customer's.

HLR isn't a legal requirement the way TPS screening is — but on any list of meaningful size, the cost of the lookups is comfortably less than the cost of dialling the dead numbers they remove.

Doing both, properly

A clean outbound list is screened on a schedule, not once: TPS and CTPS for compliance, HLR for hygiene, with the results logged so you can evidence what you did. The mechanics matter — register updates, lookup costs, and the audit trail all have to be wired into the dialling workflow rather than run as an occasional manual chore that lapses the moment someone's on holiday.

For firms running their own dialler, this is a build: register feeds, a lookup service, suppression logic, and reporting. For firms on a managed dialler estate, it's the kind of control that should be switched on by default and running nightly — screening the list, removing the dead and do-not-call numbers, and keeping the evidence.

Telebyte builds TPS/CTPS screening and HLR validation into the contact-centre estates it runs — automated, scheduled, and logged for compliance evidence, integrated directly with the dialler. If your list hygiene is a manual job that keeps slipping, tell us what you're running and we'll show you what "switched on by default" looks like.