During voice-over-Internet-protocol calls, data are gathered about packet loss on the path over the IP network. An algorithm (in the preferred embodiment, the Sliding Window Exponential Average Algorithm) is used to evaluate the packet loss. The Sliding Window Exponential Average Algorithm allows for past performance to be considered along with current performance. If the resulting evaluation fails to meet predetermined criteria, the path over the IP network is blocked and calls are routed over an alternative.