Patent ID: 7362707

Claim:
A method for determining latency for a real-time transport protocol (RTP) data flow between a first call endpoint and a call second endpoint, said RTP data flow transiting through a media router, comprising the steps of: intercepting a first RTCP sender report sent from the first call endpoint to the second call endpoint, and a first RTCP receiver report sent from the second call endpoint to the first call endpoint, each first report transiting through the media router, wherein intercepting a first RTCP sender report comprises the steps of: receiving, in the media router, the first RTCP sender report, the first sender report originating from the first call endpoint and destined for the second call endpoint and transiting through the media router; transmitting the first RTCP sender report to the second call endpoint; intercepting a second RTCP sender report sent from the second call endpoint to the first call endpoint, and a second RTCP receiver report sent from the first call endpoint to the second call endpoint, each second report transiting through the media router; and determining, in the media router, a round-trip delay between the first call endpoint and the second call endpoint based on a plurality of interception times, each interception time corresponding to the time of intercepting one of the RTCP reports; recording a last session report (LSR) timestamp when the first RTCP sender report transits through the media router; marking a first timestamp in the media router when the first RTCP receiver report transmits through the media obtaining a delay since LSR (DLSR) representing processing delay in the second call endpoint; and determining the round-trip delay based upon the LSR timestamp, the DLSR, and the first timestamp.