RTP Multiplexing is a point-to-point technology which consists of multiplexers and demultiplexers. Multiplexer receives a number of streams from different sources, and then identifies the destination address and removes RTP headers of every packet and combines them into a single multiplexed packet with the same destination by adding a mini header to keep the information of every packets. Then it is sent to demultiplexer which rebuilt multiplexed packet to original packet with the help of mini header information and delivered to its destination.

Multiplexing the packets removes RTP overhead that saves the bandwidth and reduces the number of sending packets, thus decreasing the network overload, reducing the packet loss and congestion which improves the Quality of Service(QoS).

To know more about it, please check How RTP Multiplexing works?