Embodiments are directed to supporting a multicast session in a wireless communications network are provided. A request to register for an announced multicast session (e.g., a push to talk (PTT) session) is sent from an access terminal to an access network. The access terminal has a traffic channel on a first carrier. The access network determines whether the announced multicast session is being carried on the first carrier. The access network transmits a traffic channel assignment message allocating the access terminal a traffic channel on a second carrier if the determining step determines that the given multicast session is not being carried on the first carrier and is being carried on the second carrier. Thus, the access terminal need not send a connection request to be allocated a traffic channel on the second carrier, thereby reducing a channel outage during the carrier switch.