Systems and methods for determining lost packets for real-time transport protocol (RTP) data flows is disclosed. Generally, a first endpoint is connected to a second endpoint, wherein the first endpoint comprises a transceiver, software stored within the first endpoint defining functions to be performed by the first endpoint, and a processor. The processor is configured by the software to perform the steps of determining a sequence number of a received RTP data packet within said RTP data flow, storing said determined sequence number, calculating whether said determined sequence number sequentially falls within a predetermined numerical order, and if said sequence number of said received RTP data packet does not sequentially fall within said numerical order, storing said sequence number as a missed RTP data packet.