If you need to find out a phone number you called in the past or know how long you talked to someone at a certain number, you will need to get a copy of your phone bill. Both cell phone and landline bills detail incoming and outgoing calls. Phone companies retain records of phone bills for several months, if not years, so you can contact your phone company to find out any information from a previous or current bill that you need. Cell phone bills can also be obtained by purchasing a service from certain companies online, which is illegal in most cases, according to Jonathan Krim of "The Washington Post." (See Reference 1.)
Check your online phone bill account. Visit your phone company's website, and set up an account if you do not already have one. This will enable you to log in and view your past phone bills. Search for the bill from the time period you need, and download or print the bill.
Call your phone company's customer service number, and request information about outgoing phone numbers from a particular billing period. You will likely have to provide information about yourself when you call to make sure that you are the phone account holder. Phone companies will not usually provide account information to non-account holders or those not authorised by the account holder to receive account information. You can request a copy of your phone bill to be sent to you, but you may have to pay a fee for this service. The customer service representative may be able to e-mail you a copy of the bill for free, however.
Search your phone bill for outgoing calls. A designation should be printed on the bill to indicate that the call was made from your phone. Look for words such as "outgoing," or "call to" to identify these phone numbers. The phone number that was called will be listed next to the date and duration of the call.