ytes for active speech; therefore, the 40 byte IPv4/UDP/RTP protocol header size would be a relatively large overhead. Using header compression in such cases would result in major bandwidth savings. The amount of overhead for small packets when using IP version 6 (IPv6), with increased header size of 40 bytes due to increased IP address space [8], would be even larger. In low bandwidth or congested networks, the use of header compression may yield better response times due to smaller packet sizes. A small packet may further reduce the probability of packet loss [2]. It has been observed that in applications such as video transmission over wireless links, the use of header compression does not improve the video quality in spite of lower bandwidth usage. For voice transmission, the voice quality may improve while utilizing lower transmission bandwidth. In summary, header compression helps improve network transmission efficiency, quality, and speed by decreasing protocol header overhead, reducing the packet loss, decreasing interactive response time, and increasing network core users per channel bandwidth means less infrastructure deployment costs. Figure 5-2 illustrates the structure of IPv6, UDP, and RTP headers. The IP protocol together with transport protocols such as TCP or UDP and application-layer protocols (e.g., RTP) are described in the form of payload headers. The information carried in the header helps the applications to communicate over large distances connected by multiple links or hops in the network. This information consists of source and destination addresses, ports, protocol iden- tifiers, sequence numbers, error checksums, etc. Under nominal conditions, most of the information carried in packet headers remains the same or changes in specific patterns. By observing the fields that remain constant or change in specific patterns, it is possible either not to send them in each packet or to represent them in a smaller number of bits than would have been originally required. This process is referred t