A Simple Internet VoIP Board

摘要

This article describes a full duplex Internet audio board (a "VoIP" board) using a PIC? microcomputer and a Lantronix XPORT Ethernet module. This board sends and receives (approximately) 16 user datagram protocol (UDP) packets per second, with 512 payload bytes per packet. Each payload byte expresses an 8 bit audio sample, taken 8000 times per second. The message format of 8 bits per sample and 8000 samples per second was as a matter of convenience and simplicity, and is not compatible with any common VoIP standard. Indeed, "VoIP' is actually a "buzz word" and does not really identify any "formal" internet protocol. Several audio formats are commonly used on the internet, but none seem to be predominant.