Group chat function
Group chat allows communication between different users who have been added to the group. However, group chat involves a risk with regard to data privacy because this group might include contacts who are known to the administrator of the group but who do not know each other, i.e. who do not have each other's phone numbers. But phone numbers of all added WhatsApp users are visible to all group members. They cannot decide on whether to disclose their phone numbers to other users or not. If they have not configured that their profile is only visible to their contacts, not only phone numbers but also profile pictures, the user's status, etc. are disclosed to other users without them having agreed to the use of their (personal) data. We recommend you to ask users in advance whether they agree to being added to a group chat and to inform them that their number will also be visible to other chat members or to make sure that a user's contact details are not disclosed to other chat members. This is possible, for example, by using the Broadcast function, which allows sending a message simultaneously to several users without having added them to a group. The recipients will receive these messages in their personal chats and will not know who else receives this message apart from them. A group chat, i.e. recipients of the message communicating with each other, is not possible this way.
Advertising law
According to general understanding, advertising is everything that can contribute to the sale of a good or provision of a service. Basically, almost all actions of a company can be understood as advertising because, in the end, a well-working customer support can also result in satisfied customers purchasing goods or services of this company again. It can be argued whether the preceding example really is advertising. However, there are purposes for WhatsApp in corporate communication for which the answer is clearer: regularly sending newsletters to customers, sending offers of the company, etc.
Make sure that the regulations and provisions of data protection and unfair competition legislation (in Germany, UWG) are observed. Both regulate that users have to consent to the use of their data for those purposes. Users have to agree to receive promotion material electronically.
Mostly, the double opt-in procedure is used. This means, that a user's contact details have to be verified twice to make sure that they are aware that they allow advertising through their phone numbers. If the WhatsApp users interested in receiving promotional material add their mobile phone numbers in a form provided on the company website, they receive a WhatsApp message to their phone numbers that has to be answered with a defined word that may be mentioned on the website, such as "Start". This procedure can mainly guarantee that the person who has entered his/her mobile phone number in the mask also agrees to receive adverts. It is also possible that the user contacts you through a WhatsApp number mentioned on your corporate website, for example, and sends the defined word, such as "Start", to subscribe to the newsletter. The user's active action is required to signalise that he/she agrees to receive promotional messages. However, you have to inform the users what they can expect when they subscribe to your newsletter. You must give information about extent, contents and frequency of the newsletters or offers, and you have to inform the customers about what personal data are collected and where they are transmitted to. In addition to the WhatsApp contact number published on your website, you should also state information regarding data privacy and how users can unsubscribe from your WhatsApp communication.