eg. An electrician has put their mobile number on a website to attract business. Can I legally contact that electrician to tell them about a product that he/she may be interested in? .. Everything is based in the united kingdom.
Organisations must not send marketing texts to individuals without their specific, valid and prior explicit consent. This consent must be recorded and kept as proof of consent. There is a limited exception for previous customers, which is known as the soft opt-in. A soft-opt in only applies if the organisation have obtained the contact details in the course of a sale (or negotiations for a sales) of a product or service to the customer; they are only marketing their own similar products or services; and they gave the customer an opportunity to opt-out of the marketing, both when first collecting the details and in every message thereafter.