A method for displaying format identifier bits in a compressed mode frame, in which the information contained in the frame is time-compressed, so that within the compressed frame a transmission slot exists. The format identifer bits are obtained by dotting a corresponding code word, and in the compressed mode the format identifer bits are displayed in the corresponding compressed frame. During display of the format identifier bits, at least one format identifier bit is re- displayed at the format identifer positions, so as to occupy all the format identifier locations by means of a format identifier bit. In the compressed mode even the original dotted format identifier bits are displayed at the corresponding format identifer locations of the compressed frame.