This invention relates to a communication system (200), user equipment (201,211) and method of performing a conference call. The communication system (200) employs discontinuous transmission and has a plurality of user equipment (201, 211, 213, 215) and a fixed network (205, 207, 208). It further comprises a speech metric processor (225) for determining if speech is originating at the user equipment. The system also comprises a silence descriptor frame generator (229) which generate silence descriptor frames if no speech is originating and a conference call processor (231) for determining if a call involving the user equipment is a conference call. Furthermore the communication system comprises means (229, 239) for suppressing silence descriptor information of the silence descriptor frames if the call is a conference call. The invention is applicable to cellular mobile radio communication systems such as UMTS.