The introduction of IP-based services to the realm of television broadcasting, television receivers and set-top boxes, opened possibilities for different, new applications for the users in front of their TV screens. IPTV, IP-based communications, social networking and web browsing are among the newest addons to the traditional digital TV concepts. This paper presents an integration concept and the implemented solution of a communication client application for a set-top box device. The communication client is provided as an add-on to the set-top box in the form of USB flash thumb drive. In addition to the voice call and messages, more advanced challenges are recognized and implemented for this application, with regard to the ubiquitous computing concept: context-aware features including an automatic profile selection based on the activities and the availability of people watching the TV, as calculated by the use of embedded sensors and proposed algorithms; the announcement of the selected profile by the use of RGB lighting effects for the RF-controlled RGB luminaires in the living room. These suggested features aim to improve the two most general usability problems of communication client applications applied to the specific set-top box solution. Firstly, interrupting the users by the notifications produced by the application can induce negative effects to user satisfaction and/or stress, if those notifications unexpectedly occur during engaging activities, such as watching the favorite TV show or talking to a friend in the room. Therefore, automatic profile selection based on detected user activities can mitigate these situations and provide the most suitable means of notifying the user for each specific situation of his/her engagement. Secondly, ignorance of the selected profile by other people interacting in person is accounted for by the announcement of the availability by using lighting stimuli.