In this paper, we study the impact of dedicated channel (DCH) transmission error on the performance of the application layer in universal mobile terrestrial system (UMTS) networks. We simulate a UMTS network with fully implemented protocol stack and study the impact of transmission error in the physical layer on the throughput and the delay variance (jitter) as performance metrics in the application layer. Our simulation results indicate that the net error rate for the delivered data in the application layer in acknowledged mode (AM) is smaller than that of unacknowledged mode (UM) however, in both AM and UM modes the channel throughput perceived in the application layer is decreased by increasing channel error rate in an approximately linear fashion. Simulation results also indicate that increasing/decreasing channel error rate in the physical layer has no significant impact on the delay variance in both AM and UM modes.