The Swiss mobile phone payments company Echovox Group said last week that its Zong service has processed transactions for 10 million users this year.

The announcement is a rare glimpse into the alternative payments market, where processors seldom disclose data about their transaction volume.

"Everybody has been pretty tight-lipped about how they are doing," said Hill Ferguson, Zong's vice president of product management and marketing. "We thought it was time."

Zong, which was introduced in 2008, focuses on impulse purchases in online games and other types of digital content, Ferguson said.

The Zong alternative payment system enables consumers to bill their purchases to their mobile phone accounts and has been integrated into applications on the social networking sites operated by Facebook Inc. and News Corp.'s MySpace unit and with virtual worlds and gaming sites including Gaia Online and Outspark.

Ferguson said the average transaction is about $9, but he would not provide any details about the average number of transactions per user.

Echovox was launched in 2000 to collect the fees generated by people using text messages to submit votes for televised competitions in Europe.

To use the Zong service, customers enter their 10-digit mobile number into the Zong payment field on their computer.

The Zong system then sends by text message a four-digit passcode, which the user enters into the computer form to complete the transaction.

The transaction is then billed to the consumer's mobile phone account and appears on their monthly statement.

The merchants are paid only after the consumers pay their monthly phone bills, which in some cases can take as long as 30 to 60 days, which is much slower than card transactions. Card payments typically settle in a few days.

Ferguson said using cards online can require about 70 keystrokes to enter the card number, the expiration date and other details about the user.

"It needs to be as easy and frictionless as possible so the customer won't bail out on the transaction," he said. "It opens up a whole new audience of buyers for these game publishers."