Abstract: In Cellular networks, blocking occurs when a base station has no free channel to allocate to a mobile user. When a user moves from one cell to another then sometimes handover does not exist and call blocking occurs. Handover is the process when call transfers from one cell to another. In case of complete Handover blocking does not takes place. There are some techniques to remove call blocking such as Handover Prioritization Schemes, Auxiliary station, Guard Channel Prioritization Schemes, Call Admission Control Prioritization Schemes, Handover Queuing Prioritization Schemes. The main goal of this research paper is to investigate the handover research issues and developing schemes which can handle handovers traffic in order to support on-going calls when mobile users are switching between base stations.