A wireless communication system uses a circuit switched link between a wireless unit and a base station to establish a data session with a network device in a packet data network. After the data session is established, the data session can proceed using a packet switched link between the wireless unit and the base station. By using the circuit switched link to send data session setup packets, the system avoids the delay associated with requesting and being allocated wireless resources in sending the setup packets using the packet switched link. Decreasing the delay associated with setting up the data session improves the data rate and throughput between the wireless communications system and the packet data network. For example, in an exemplary CDMA system, a circuit switched link is established to carry primary traffic (such as voice) and secondary traffic. The setup packets for the data session can be directly sent as secondary traffic on the circuit switched link, thereby avoiding the delay associated with sending the setup packets over a packet switched link. In this way, the round trip time (RTT) associated with setting up the data session can be reduced to improve the overall data rate and throughput through the wireless network to the packet data network.