Log in, then find the user's ad or profile and use the "call" option. We strongly recommend that you contact the advertiser by phone 1 day before the start of the course or a diving trip the latest, to determine the details. All diveTarget.com ™ users are asked to provide their mobile phone number. Our system, as part of account authorization, in most cases checks whether a given phone number is active. We do this so that we can be sure that users will be available to other users as part of the booking process, but for obvious reasons we cannot guarantee that the number will always be active.