The present invention provides a system and method of calculating a service disruption in a communication network comprising network elements, including nodes connected via links and at least one originating node. Each node is able to detect a failure in an adjacent network element. Upon detection of a failure, a first timestamp is generated. The detecting node generates a release signal which is transmitted, together with the first timestamp, to an originating node which releases the affected connection. The originating node establishes a new connection and initiates a new call. Upon establishing a new connection, a node affected by the failure, which forms a part of the new connection, records a second timestamp. The second timestamp is chosen to reflect, as closely as possible, the actual time of restoration of service in the network. Service disruption is measured as a difference between the first and second timestamps.