In a Cisco IP Telephony environment, the Call Manager software controls many aspects of the IP Phones. In addition to call handling and some configuration, the Call Manager server can also cause the IP Phones to reset and restart. Remotely controlling the sets can be quite useful during troubleshooting, or reconfiguration. Knowing whether to use reset or restart isn't really important in the grand scheme of things, but it's always the little things that make or break your day.
A reset is the equivalent of a cold boot. The phone will turn its power off and on and then put itself through the normal boot process. A restart is less dramatic, and only causes the phone to release its registration with the Call Manager and then register again.
To some extent, which one you choose may depend on whether you're troubleshooting a problem with a phone, or a problem with the server or connection. If you're just testing things like name and number resolution, and higher-level call-signaling protocol functionality, then you can stick with the quicker restart command. On the other hand, there are times when you want to reset the phone completely.
One important thing to remember, however, is that the restart command doesn't not cause the phone to load its config from the TFTP server, so if you've made changes to the configs and issue a restart, don't be surprised when the phone doesn't reflect the new configs. This is an example of a job for reset.
Thomas Alexander Lancaster IV is a consultant and author with over ten years experience in the networking industry, focused on Internet infrastructure.