The authentication mechanism plays a key role in roaming, where the mobile user often needs to integrate and secure roaming service over multiple foreign agents. Designing a secure mechanism in Global Mobility Network (GLOMONET) is a difficult task due to the computational and processing limitations of most mobile devices, as well as the wireless nature of communication environment. Unfortunately, most of the authentication schemes that have been proposed have failed to achieve their goal and have security flaws against impersonation. Thaus the authors propose AMAPG, as a cost-efficient remedy version of the protocol which provides desired security against various attacks.