The performance of nonblocking switch with two kinds of correlated input calls is analyzed. We define two kinds of call as the waiting call and the immediate call, and assume that the immediate call has the priority over the waiting call. If one kind of calls is larger than maximum throughput, the ratio of the corresponding kind of calls to the total traffic must be restrained in some range. We derive the maximum ratio of the waiting call. For the derivation, we propose two approximate methods. It is shown that, if the traffic density of the immediate call is smaller than that of the waiting call, our approximate methods are useful to derive the maximum ratio of the waiting call to the total traffic. And we indicate that, if the traffic density of the waiting call is larger, the ratio of the waiting call to the total traffic must be diminished.