Citizens call 911 in different ways. Calls come into the center from landlines, cell phones, over the internet (VOIP), or from a telecommunication device for the deaf (TDD). Landlines are optimal for fast location information because each landline is registered with the phone company. Upon receiving a call, operators are given the name, address, and phone number for the caller. 911 calls from VOIP line have the same immediate information, but may not be accurate. Landline information is automatically updated by the phone company, VOIP information needs to be updated by the user. If a user forgets to update, operators will not receive correct information. Enhanced 911 requires cell phone carriers to place GPS receivers in phones in order to deliver more specific latitude and longitude location information, which is accurate within 50-300 meters. However, sometimes, operators are still not able to get a cell phone location. Regardless of how a citizen calls for help, the operator must verify the location information and phone number.