A system and method for verifying, authenticating, and providing notification of a transaction, such as a commercial or financial transaction, with and/or to at least one party identified as engaging in the transaction and/or identified as having a potential interest in the transaction. A central system accepts information regarding a transaction, including information about at least one party identified as engaging in the transaction, such as by a credit account number or Social Security number or merchant account number, and/or identified as having a potential interest in the transaction. Based on the information regarding the transaction and any supplemental information the central system determines, the central system communicates with and/or to at least one party and/or additional or alternative parties, via at least one communications device or system having a communications address, such as a telephone number or Short Message Service address, predetermined as belonging to the at least one party and/or additional or alternative parties. Via said communications, at least one party identified as engaging in, or having an interest or a potential interest in, the transaction may be notified of it, and may further be enabled or required to supply additional verifying or authenticating information to the central system.