If a cell phone is purchased and activated on one of the large networks (such as AT&T, Verizon, Spring, MetroPCS, T-Mobile, etc. and the subscriber is a "contract" customer - I.E. the customer buying the cell phone is on a monthly contract for two years, the subscriber information is automatically added to the telephone carrier's directory. However, if someone purchases a pre-paid cell phone (such as NET10, or other prepaid service) the subscriber information is usually not added to the carrier's directory as there is no subscriber information provided at the time of purchase. Thus, certain cell phone lines, and certain VOIP lines will not report owner or subscriber information on a reverse phone lookup.
If you ever find someone's cell phone, you should always try to find out who the owner is and return the cell phone back as soon as possible. You can find out the owner's name for free on many reverse phone search websites like http://reversephonelookupnumber.org/reverselookup/
They also will provide you with the contact information. Alternatively, you could find out the owner's name through the owner's cell phone provider.
Contact the cell phone provider. You may find
it in the contact list. Alternatively, you can look on the cell phone
provider's website for the contact information.
Tell the representative that you found someone's phone. Give the phone number, and any other additional information the representative may need. The representative will then give you instructions on how to return the phone to the owner.
More info
There is no database dedicated to storing cell phone numbers. However, many online phone books allow free look up of cell phone numbers. There are also many sites that will do reverse searches for a small fee, all you need to provide is the phone number. Here is how to look up somebody's cell phone number for free.
Not everyone's cell phone number is listed. If the person you are looking for has an unlisted cell number you might need to try using a pay search engine.
Suspicious, annoying, harassing phone calls
Investigate Spouse, Lover or B/G Friend
Monitoring kids contacts for safety
Stop telemarketing calls
Report Dead Calls (phone rings, but you hear nothing at other end of the line)
CallerID Spoofing - You receive a call with a fake or bogus CallerID. Look up the number to verify the owner.