Performing handoff of a mobile station between different types of wireless network controllers

A method of performing handoff of a mobile station from a source wireless network controller to a target wireless network controller, comprising:

• the source wireless network controller determining a handover event for the mobile station from the source wireless network controller to the target wireless network controller;
• in response to the handover event, the source wireless network controller transmitting a service redirection message to the mobile station;
• after sending the service redirection message, the source wireless network controller receiving an origination message from the mobile station;
• after receiving the origination message, sending a first message from the source wireless network controller to the target wireless network controller, the first message bring provided to initiate the handoff, wherein the source and target wireless network controllers communicate with the mobile station according to different protocols;
• and
• receiving, by the source wireless network controller from the target wireless network controller, a second message responsive to the first message, wherein the second message contains a request to perform signal strength measurements of selected cell segments neighboring the target wireless network controller, and wherein the second message contains information to enable identification of the selected cell segments neighboring the target wireless network controller for which signal strength measurements are to be performed.