This paper proposes a QoS-based strategy for call admission in mobile cellular networks, based on the past system's behavior. The algorithm is an extension of the conventional guard scheme (CGC) and demonstrates improvements compared to CGC. It reduces the new call blocking probability, increases the total carried traffic and keeps the forced call termination probability almost unchanged. The proposed policy falls into the class of fractional guard policies. Each cell builds cumulative statistics from its "experience" and accepts a new call only when predetermined handoff failure probability is not exceeded. The generic form of the algorithm is independent of cellular network topology.