A base station (110) in a wireless communications network (100) counts mobile stations (114) receiving broadcast content via multi-user channel. The base station broadcasts (608) a repeating message identifying at least one broadcast content stream and, for each stream, a REGISTER (R) or DO NOT REGISTER (DNR) indicator. Mobile stations periodically re-examine (722) contents of this message. When the indicator is R for a broadcast content stream, mobile stations whose users have elected to receive it send (714) the base station a registration message for that stream. When the number of registered mobile stations reaches (612) a prescribed number, the base station changes (614) the indicator to DNR. When the indicator is DNR for a broadcast content stream, mobile stations refrain (712/716) from sending any registration message for that broadcast content stream. The base station may institute a recount (618) by resetting the indicator to R.