NEW YORK (MainStreet) -- You know how it is: A friend picks up some concert tickets, you meet him at the show and then suddenly realize you don’t have enough cash to pay him back.

But suppose you could whip out your cell phone and settle up with a few clicks?

In fact, you can. Person-to-person payment systems, or P2P services, have been around for some time. PayPal is the best known, allowing users to send money to other individuals. Now, the explosion of smart phones and tablets makes it easy to make a payment, or receive one, just about anywhere -- sometimes with a fee, sometimes not.

PayPal has mobile-phone apps that allow P2P payments. So do many banks, some cell service providers and other firms. But, just as it took consumers a while to trust ATMs and online banking, P2P services take a little getting used to. How do you know that a service is safe, efficient and affordable?

As with any service, it pays to read the fine print in the service provider’s contract or user agreement. Look for descriptions of security measures like encryption, and find out how disputes are resolved. What, for example, is the maximum loss for which you could be liable?

The Federal Deposit Insurance Corp., the agency that insures bank deposits, says there can be some real benefits to using a P2P service available through a bank.

“The P2P services offered by banking institutions have the same federal consumer protections that you get when using your credit or debit card if the payment is funded by linking it to your credit card or checking account, respectively,” the FDIC said in its recent Consumer News bulletin [PDF]. “That means, for example, that if someone steals your smart phone and uses it to transfer money, you may have limited or no liability for that unauthorized transaction provided you report the problem in a timely manner.”

Mobile payment services from non-banks may not offer as much protection, according to the FDIC.

Also make sure the service you choose is not overly limited. The FDIC says some will transfer funds between any two people who have bank accounts, while others require that sender and recipient both be signed up with that provider.

Some services require that the sender key in the recipient’s bank account and routing numbers, which can be a hassle and a security issue. Others require only that the sender know the recipient’s email address or cell phone number, and the service sends the recipient a notification with instructions on how to complete the transaction.

To find a service, the FDIC recommends starting with the bank at which you have your checking, savings account or credit card. That way, you won’t have to set up and fund a separate account for your P2P transactions.