There are now 4 billion mobile phone connections worldwide, according to the GSMA, the leading global trade association for wireless carriers.

The milestone is said to reflect the growth of the mobile market, convincing the GSMA to project 6 billion mobile phone connections worldwide by 2013. But the number of connections should not be confused with the number of subscribers.

"Because of the multiple use of SIM cards by subscribers, the actual number of subscribers will be lower than the number of connections," said David Pringle, spokesman for the GSMA, London.

For example, an estimated 20 percent of the total mobile connections in Western Europe are due to the use of multiple SIMs.

The research, from the GSMA's Wireless Intelligence unit, comes a week ahead of the GSMA's upcoming Mobile World Congress conference Feb. 16-19 in Barcelona, Spain.

The growth in the number of connections is attributed to a couple of reasons. First, the integration of mobile into previously unconnected devices and then, subscriber enrollments in emerging and developing markets.

It is harder to track the number of subscribers simply because one mobile phone often is shared by many consumers in some developing countries.

Thus, wireless connections is the primary currency for the GSMA to use to measure growth in the mobile industry.

Connections and connecting
Regardless of the measurement yardsticks, the increase is good news for carriers.

"Four billion connections is 4 billion connections for operators that represents usage of their services," Mr. Pringle said.

"But it also suggests the embedding of mobile in these different devices and also the rapid growth in these different countries," he said.

China and India offer the highest growth rates in the number of mobile connections. The United States is third after those countries in terms of the number of connections.

The GSMA is relying on this rapid growth in mobile connections to push its mobile broadband, mobile lifestyle and mobile planet efforts.

The upcoming Mobile World Congress conference -- expected to attract 50,000 delegates, a 10 percent decrease from last year -- will reflect that approach in the speaker lineup and session agenda.

Opportunities in the developing world, especially the effects on marketing, will be one of the focuses of the event.

"I think probably the most significant thing in global terms is the large number of people in the developing world [going mobile]," Mr. Pringle said.

"They are now reachable because they have a mobile connection," he said. "A lot of these people have never had a fixed-line connection. They've been outside of the information economy.

"The only way to have reached these people in the past would have been to be physically present in the place they are. So, if you are an advertiser or a marketer, you had to be physically present -- that could be in the form of television or radio advertising.

"For the first time you can interact with these individuals on a one-to-one basis [with mobile]."