A method of extending, for enabled stations, the number of information states conveyed by a signal employed by legacy (non-enabled) stations. The additional information states may convey a Broadcast/Multicast Service (BCMCS) Indication by means of tristate modulation, including binary phase shift keying plus zero amplitude. A signal, such as a quick paging (QP) message, is selected because legacy receivers combine subunits of the message before the data content is determined. Complementary modulation is applied to the subunits, such that legacy combining renders the message information indistinguishable from harmless messages, yet distinguishable as a distinct additional information state in a legacy receiver. For example, a legacy receiver cannot distinguish a new QP message from a “zero” signal, due to application of inverse BPSK to the subunits. An enabled station may thus detect new information, such as a BCMCS Indicator, in a manner that is compatible with legacy stations.