A Perl program that sends a voice stream using RTP (Real-time Transport Protocol) is show below. The default codec for input voice is 16-bit linear, but u-Law (G.711) and some other codecs can be used. The port numbers and the IP address of the receiver are specified in this program ($REMOTE_PORT_RTP, $LOCAL_PORT_RTP, $ip, etc.). RTCP (Real-Time Control Protocol) can also be handled, but no specific control is intended. A detailed description will be given in future, but it will be explained when it becomes necessary.