DnD service makes you number register into the do not call registry so that telemarketers cannot call you. You can easily activate Do Not Disturb Service (DnD). Here’s what Vodafone says about the privacy of users -
Vodafone respects my privacy and takes great care to protect my number and personal details. Sometimes they might try to get in touch to let me know about a recommended tariff, a new offer or an innovative service that may be of interest to me.