Patent ID: 7529208

Claim:
A method of performing a handoff in a communication system, comprising: performing a handoff of a first call of a subscriber unit from a first fixed station to a second fixed station by; transmitting a handoff required message from the first fixed station to a switching center; transmitting a Handoff Request message from the switching center to a second fixed station to request a handoff to the second fixed station; transmitting Null Forward Traffic frames from the second fixed station to the subscriber unit; transmitting a Handoff Request Acknowledge message from the second fixed station to the switching center to acknowledge receipt of the Handoff Request message; transmitting a Handoff Command message from the switching center to the first fixed station to initiate the handoff; transmitting a Handoff Direction message from the first fixed station to the subscriber unit to inform the subscriber unit of the handoff; transmitting an Acknowledge Order message from the subscriber unit to the first fixed station to acknowledge receipt of the Handoff Direction message; transmitting a Handoff Commenced message from the first fixed station to the mobile switch to indicate that the handoff has commenced; transmitting at least one of Reverse Traffic Channel Frames and a Preamble from the subscriber unit to the second fixed station; transmitting a Handoff Completion message from the subscriber unit to the second fixed station to indicate that the handoff has been completed; and transmitting an Acknowledge Order message from the second fixed station to the subscriber unit to acknowledge receipt of the Handoff Completion message, receiving an In-traffic System Parameter Message having a packet zone identifier from the second fixed station over an air interface; detecting a change in packet zone and perform a handoff of a concurrent second call, wherein the first call is an active call and the second call is a dormant packet data call.