The mobile payment service will be offered to all Citibank customers in the US, with a focus on Boston, Chicago, Maryland, Philadelphia and New Jersey.
Customers can participate by activating and connecting the mobile service to their Citi chequeing account or setting up a new mobile payments account via the bank's Web site.
Subscribers can then send and receive money using their handset's Web browser, SMS text messaging or the downloadable mobile application. To transfer funds from their account, participants just need the recipient's phone number.
Debby Hopkins, chief innovation officer, Citi, says: "Citi's goal is to be everywhere our customers need us to be and interact with them however they choose - in person, online, while in transit or on their mobile phone."
Citi and Obopay launched a limited P2P payments trial for the bank's credit and debit card customers in Boston and Chicago in February 2007.
In a separate move, Citi has launched a business-to-business electronic payment system for corporations, financial institutions and public sector clients.
Developed with MasterCard, Citibank Paylink for Cards integrates a purchasing card into a client's accounts payable system, helping the customer streamline vendor payments, says the bank.
This system passes information to all necessary parties - from settlement to reconciliation. The MasterCard Payment Gateway acts as the network between Citi, the buyer and the supplier to simplify the entire payment process.