As more consumers begin surfing the Web and sending e-mail messages on cellphone and hand-held devices, along comes a new worry: worms and viruses spread via Internet-enabled handsets.
The problem is still small, with only a few cases reported globally. But as operating systems in cellphones become standardized, hackers will probably begin focusing on vulnerabilities in those systems as they have with personal computers.
And as cellphones and personal digital assistants connect to the Internet at ever faster speeds, more users will be able to download files with attachments -- some of which may be infected.
Asia, where high-speed networks and text messaging on mobile phones are common, is the most vulnerable to these threats. As carriers in Europe and North America adopt similar technology, they will confront the same kinds of hazards.
Telecommunications companies currently spend as much as US$8 billion a year fixing handsets with programming errors, faulty mechanics and other problems. Now some are scrambling to prevent virus attacks that could cost carriers millions of dollars more in repairs and lost business.
"The danger to mobile phone networks is probably five times bigger than with personal computers because very few people are focused on this problem now," said Andrew Cole, senior vice president at Adventis, a Boston-based consultant specializing in telecommunications issues.
"The dominant form of messaging is going to be cell-to-cell, so this could escalate very rapidly and overload phone networks. What if viruses phone 911 randomly?"he asked.
That, in fact, is what happened in Japan in 2000 and 2001. NTT DoCoMo, the country's largest cellular phone provider, received complaints from customers who were being sent messages that froze their screens and automatically dialed 1-1-0, the emergency line to the police in Japan.
"The incident was definitely unexpected, that's for sure," said Nobuyuki Watanabe, senior director of the Terminal Application Group at DoCoMo.
That event was a shock because the company is spending billions of dollars introducing its high-speed third-generation, or 3G, network that allows users to download data up to 40 times faster than conventional mobile phone networks. A rash of viruses might turn off users to the new network before it was released.
Eventually, DoCoMo dealt with the problem by installing special security software on its servers and new handsets, which were also being bombarded with unwanted commercial e-mail and text messages from advertisers, dating clubs and other marketers.
DoCoMo blocks about 55 percent of the 1 billion text messages that reach its servers each day because of suspicious return addresses or attachments. Another 26 percent of those messages are blocked by DoCoMo users who have programmed their handsets to turn back unwanted mail or spam.
Spam, though, is relatively benign compared with viruses and worms that could attack handsets. In typical cellular phones, the central processing unit that serves as the brain of the handset are about as sophisticated as those in personal computers five or six years ago.
For now, most mobile phone companies customize the operating systems for their handsets, so the number of people using any one platform is small compared, to say, to the number of people using Microsoft Outlook, a standard e-mail program for personal computers.