Synchronization of client application data between pots telephone and content portal through PSTN

Methods, Plain Old Telephone System (POTS) phones, and computer program products are provided for synchronizing client application data, such as names and associated telephone numbers in a phone book, between the POTS phone and a content portal through a Public Switched Telephone Network (PSTN). A dial-up data communication connection is established between the POTS phone and the content portal through the PSTN. A determination is made at the content portal that the POTS phone is associated with client application data in the portal database of the content portal. Client application data is synchronized between the POTS phone and the portal database in response to the determined association between the POTS phone and client application data in the portal database.