Data protection: Data protection ensures that individuals' general right of privacy is not affected through use of their personal data, whether collection, processing or utilization. In addition to data protection and privacy laws, data protection can also be safeguarded through technical and organizational means.

Data security: This term describes the technical/organizational aspect of ensuring secure data processing. Data security is ensured when the improper use of data is ruled out, regardless of whether personal or impersonal data is involved, such as the company's sales data.

Personal data: Sometimes referred to as "private data", paragraph 3 (1) of Germany's strict data protection law describes "personal data" as "any information concerning the personal or material circumstances of an identified or identifiable individual (the data subject)". This is data that contains information about the data subject or information about a related situation. Examples of personal data include name, phone number, ID card number or bank account number. Under the German law, personal data is always the data of a natural person, which means only data from natural persons are subject to data protection regulations.

Secrecy of telecommunications: Secrecy of telecommunications, along with postal secrecy, is contained in Article 10 of the German constitution, making it a basic right. It is described in more detail in paragraph 88 of the Telecommunications Act. Secrecy of telecommunications protects both the content of the communications and the related information as to whether someone participated in a communication, and if so, when and where.

Data secrecy: Under paragraph 5 of the Federal Data Protection Act, anyone working in data processing is forbidden to collect, process or use personal data (data secrecy). Data secrecy goes beyond any contractual non-disclosure agreement, in that it also forbids the "internal" misuse of personal data. An example of such misuse is when an employee goes beyond the access authorizations he or she has been granted.

Need-to-know principle: Every employee is only given access to the data required for his or her function and duties. Call center employees and Telekom Shop staff, for example, need nationwide access to comprehensive customer data to meet the demands for excellent customer service. Employees in technical service, in contrast, do not have any access to customer data systems; they can only access data related to line routing.

Traffic data: Traffic data is data that is collected, processed or used in the provision of a telecommunications service. This particularly includes the number or ID of the lines being used, personal authorization codes, when the call began and ended, etc.