We all know that 800 telephone numbers represent toll free calls, but you should be equally aware that a telephone number that starts with 900 is a pay per call. Scammers will call you and leave a message to call them in regard to a contest you have won or any other ruse to get you to return the call. Once they have you on the line, they do everything possible to prolong the call and increase the charges on your phone bill. Some scammers will have you call an 800 number, but then have you press the number 9 to verify your phone number without realizing that you have just transferred the call to a 900 number.
Consider having your phone service provider block access to 900 numbers from your phone. The FTC regulates 900 numbers and requires that you be asked at the start of the call to pay with a credit card or to make billing arrangements at that time. If you have been scammed by a 900 number charge that appears on your phone bill, call your phone provider as tell them to remove the charge from your bill.