UK rules, not North American ones
Keep Outbound Legal Under UK PECR Rules
This is where imported playbooks go wrong. A Canadian or American agency will often apply consent rules that do not match UK law, then either break it or refuse tactics that are perfectly lawful here.
Under the Privacy and Electronic Communications Regulations, the rules turn on whether the contact is a corporate subscriber or an individual subscriber. Sole traders and many partnerships count as individuals.
Two practical consequences. Emailing a named engineer at a limited company does not require prior consent under PECR, though UK GDPR still governs the personal data. Cold calling that same factory does require register screening first, and a registration can take up to 28 days to become active.
We screen before any call list is used, we display a number on outbound calls, and we keep a suppression list of anyone who asks us to stop. Ask any agency to show you their screening process before they touch your prospect data.
Sources: ICO guidance on business to business marketing and telephone marketing, plus the Telephone Preference Service. Take your own legal advice on your specific data.