Methods, media, and systems are provided for optimizing the use of broadcast channels for group communication streams on a wireless telecommunications data network. Transmission proxy servers associated with base stations are used to determine whether a broadcast channel or unicast channel is most efficient for transmission of a group communication stream. Transmission proxy servers examine factors such as number of users, movement, duration and bandwidth required to make the channel determination. A contact management server coordinates the authentication across multiple access networks in coordination with the transmission proxy servers. Delivery can be more flexible, higher service levels can be more easily guaranteed, and secure but seamless handoffs are possible utilizing the claimed embodiments.