A system provides a media relay for real-time communications (“RTC”). The system receives, by a signaling server, a first signaling message from a first client including one or more first candidate transport addresses of the first client. The system generates a modified first signaling message by inserting a transport address of a relay server into the first signaling message, and transmits the modified first signaling message to a second client. Then, the system receives a second signaling message from the second client including one or more second candidate transport addresses of the second client. The system generates a modified second signaling message by inserting the transport address of the relay server into the second signaling message, and transmits the modified second signaling message to the first client.