Abstract: Network telephony monitoring systems are provided herein. In one example, a monitoring service is configured to present an interface for a network telephony monitoring system to receive link metrics for media legs of a packet voice call that extends from an originating network over a plurality of transport networks, with each of the media legs spanning between border control nodes of the plurality of transport networks. A leg quality processor is configured to process the link metrics to differentiate quality degradation of the packet voice call among one or more of the media legs.