Cell phones are becoming the preferred method over land lines. Land line phones are tied to specific addresses, allowing easy plotting on computerized maps, but cell phones are designed to allow movement; however, the technology is improving on a continuous basis to assist dispatch centers.
Please be aware that there are many internal happenings when you dial 911 from your cell phone. When you dial 911 from your cell phone the signal goes to the closest cell phone tower and that tower sends your call to a pre-determined Public Safety Answering Point (PSAP). The dispatch center you receive immediately may not be the dispatch center of the county you are in and you will then be transferred to the correct agency.
Disconnected cell phones are still capable of calling 911. Please do not give these phones to your children as toys.