Chapter 6. Connecting to the World with sipXecs
Eventually your users will want to dial out of the system. Gateways provide the connectivity required to reach other systems. These systems can be other sipXecs PBX's, traditional phone lines, or Internet Telephony Service Providers ( ITSPs).
Connecting the IP phone system to the outside world is one of the most difficult tasks in making the phone system work. If the network infrastructure is configured properly for quality of service, the connection to the outside world can most likely be the source of any call quality problems.
Traditional analog Plain Old Telephone Service (POTS) lines are the largest source of frustration. If you can avoid them by utilizing a digital type of service or an ITSP, by all means take that avenue. For those not so lucky, you'll learn more about them then you ever thought you needed to. Typically, volume levels, line disconnect, and echo are the most common problems. Most gateways will have some advanced settings...