Aspects of the invention are directed to signalling extension frames in a telecommunication system. Extension-frame-signalling data may signal whether one or more extension parts are present in one or more gaps in time between data frames, when the one or more extension parts occur, and one or more durations for the one or more extension parts. The one or more extension parts may occur on the same radio frequencies as the data frames. The extension-frame-signalling data may signal when the one or more extension parts occur by signalling after which of one or more data frames in a super frame the extension parts occur. The one or more durations for the extension parts may be expressed in units of time.