A computer-implemented method is disclosed for integrating at least one first communication terminal assigned to a user as a preferred device in a static configuration of a communication system and/or for dynamically switching from a first communication terminal used as a preferred device to a second communication terminal as a preferred device for providing a one-number service using the preferred device, to which a one-number service number is assigned, wherein at least two communication terminals are statically assigned to the user and a preferred device is also dynamically assigned to the user through a virtual device. Also disclosed is communication system designed for this purpose.