Push-to-talk messages are sent via a wireless multicast channel to multiple push-to-talk groups of devices regardless of group membership. Thus, all of the devices using the multicast channel receive all of the push-to-talk messages. To separate messages bound for one push-to-talk group from those bound for another, a push-to-talk group specific orthogonal code is applied to each message. The devices in a specific group use the group specific orthogonal code to decode the received multicast messages. If a device decodes the multicast message with the correct group specific orthogonal code, then the message is decoded and the device can play the message. If a device decodes the multicast message with a different group specific code (i.e., because it is not a member of the group the message was intended for), the message is will not be properly decoded and thus will be unplayable or scrambled.