CHICAGO - If you need to pay a babysitter, send money to a kid in college, or reimburse a friend for lunch but don't have your checkbook or cash on hand, pick up your smartphone.

An increasing number of banks are rushing to offer or enhance person-to-person money transfer services. In many instances, all you need to send money to someone is that person's mobile number or e-mail address.

Person-to-person mobile payments are still in their infancy in the United States, with only 4 percent of Web-connected adults using them in 2010, according to a November report by Forrester Research Inc.

More than half of all mobile person-to-person payment users conduct such transactions at least monthly, and interest has been growing in the last three years, Forrester said.

Consider Angela Munasque, a New York writer and editor who signed up for Chase's QuickPay service in early December after she had run out of checks. She had seen Chase's QuickPay ad on TV.

"It seemed to fit my needs since I rarely write checks and do a lot of online banking already," said Munasque, 27.

Chase QuickPay transfers should take about one business day if the parties have Chase checking accounts, and two to five business days if one of the parties uses a different bank. Munasque said she had transferred funds to someone with a non-Chase account.

"It was really, really easy for both of us," she said. "It takes a couple of days for non-Chase accounts to be verified, but you don't have to stop by the bank, you don't have to call anyone."

Some consumers, though, have experienced hitches with QuickPay.

Tim Wiseman, a digital media marketing consultant in Akron, Ohio, said QuickPay had mostly worked well for him. He said he had received money in less than 24 hours.

A few weeks ago, however, a transfer of money to him by a family member seemed to end up in limbo.

"This particular QuickPay took much longer, four business days, plus a weekend," Wiseman said. "Not only that, but my family member was charged three times for the transaction."

Chase quickly resolved the situation, reimbursing the person who was charged three times, said Wiseman, who continues to use QuickPay.

Sunny Vempati, 23, a Chicago software developer who started using the service more than six months ago, said QuickPay had been handy at restaurants that frown on dividing bills for multiple parties.

Vempati said he had also used Venmo and PayPal but prefers QuickPay.

Both State Farm Bank and Discover Financial in 2010 established person-to-person payment programs powered by PayPal.

Discover introduced its Money Messenger service in October 2010. When Discover card-holders send money, PayPal sends a message to the recipients letting them know their money is ready. The recipients sign into their PayPal accounts to receive the money; if they don't have a PayPal account, they must sign up for one. The amount sent is charged to a customer's Discover card account just like a purchase.

State Farm plans to roll out new and faster enhancements to its person-to-person payment offerings starting in February.

Last month, Minneapolis-based U.S. Bank announced Pay-A-Person, which also allows customers to send money to anyone nationwide by using the recipient's mobile number or e-mail address.

Chase says that since the beginning of 2011, more than two million customers have sent more than $1.4 billion through QuickPay.

Chase also is part of a person-to-person payments consortium announced in May. Bank of America, Wells Fargo, and Chase are among the banks in a new venture called clearXchange, which is scheduled to be rolled out in 2012 to allow customers to move money using a mobile number or e-mail address, instead of providing checking-account and routing numbers.