 the SIP Trunk. The second consideration is the quality of the connection. The number of packets that the SP drops in each link of the connection is the ultimate determination of the quality of a call. A voice or video call deteriorates only in quality if the numbers of packets received are fewer than the number of packets sent. The other determination of quality is the latency of the connection. Latency is the measure of the time a packet takes to traverse a network; if the SP network has a long latency, the quality of the connection deteriorates. Voice Gateways The component of an IP Telephony system that converts the TDM connection from a tra- ditional telephony system, either a Private Branch Exchange (PBX) or a Public Switch Telephone Network (PSTN) connection to an IP connection, is known as a voice gateway. Voice gateways include several essential components including a central CPU that supports the signaling required to connect to the IP network and the TDM network and a DSP to convert the TDM connection to an IP connection. Voice gateways can generally be divided into three groups. Initially, voice gateways were created as add-on cards to PC- or server-based systems. This was convenient during the time when a rapid expansion of the features was provided by voice gateways. At this time, having a CPU-based system that allowed for independent updating of individual software components, such as the IP signaling method and the TDM signaling stack, while leveraging the add-on card that included the DSPs to allow for higher density, was the most efficient method to create a feature rich voice gateway. The second iteration of voice gateways is the form that is most popular in enterprise and small businesses today: standalone dedicated devices or a feature integrated into a router with many capabilities. These devices simultaneously provide connectivity to the PSTN, a central CPU for call processing, connectivity to the LAN or WAN, and DSPs for media processing. The important distinction is that a general purpose