Protocol and technology convergence, the core of near future communication, will soon be forming theinteroperating heterogeneous networks. Attaining a strict secure authentication without risking the QoSperformance and call success rates is a major concern when it comes to wireless heterogeneousnetworks. In order to achieve this, a generic, fast and secure, Authentication and Key Agreement protocolis to be used; a version of which is to be implemented between each two technologies. In this research,different existing EPS-EPS AKA protocols will be compared with our proposed protocol EC-AKA(Ensure Confidentiality Authentication and Key Agreement) based on security, cost effectiveness,signaling overhead, delay and performance. It is proven that EC-AKA is the exclusive protocol satisfyingthe New Generation Network’s KPIs and it will be promoted as the target generic AKA protocol inheterogeneous networks.