Classify the activity before assigning controls. Article 5 protects confidentiality of communications and related traffic data by requiring Member States to prohibit listening, tapping, storage, interception, or surveillance by persons other than users unless users consent or Article 15(1) lawfully authorizes the measure. Article 5(3) separately governs storing information on, or gaining access to information stored in, a subscriber's or user's terminal equipment.
The scope record should say whether the activity is communications carriage, terminal-equipment access, traffic-data processing, location-data processing, direct marketing, directory publication, calling-line functionality, or a national-law restriction. Do not collapse these into a single GDPR lawful-basis decision.