We propose an analytical model to assess the throughput and call blocking rate of Opportunistic Spectrum Orthogonal Frequency Division Multiple Access network constituted of multiple classes of Secondary Users (SUs) and temporarily active Primary Users (PUs) of different priorities. In the case of PUs we consider low activity wideband and high activity narrowband users. While in the case of SUs we consider subscribers transmitting real-time constant bit rate (CBR) and elastic variable bit rate (VBR) traffic. We conclude that with the increased activity of PUs, CBR traffic experiences larger throughput decrease than VBR. Moreover, blocking rate of CBR connections decreases exponentially with increased inter-arrival rate of PU, while we observe no direct correlation between obtained SU network throughput and CBR blocking rate.