General Electric Co. has barred outside instant-messaging and file-sharing programs, as well as access to personal online e-mail accounts like those offered by Yahoo Inc.
Telecom company Global Crossing Ltd. also blocks outside instant messaging and online e-mail accounts. J.P. Morgan Chase & Co. is one of many banks that blocks Internet services it can't track or monitor, including outside instant-messaging, phone and email programs.
Another big bank, ABN Amro Holdings NV of the Netherlands, also bans many consumer-communications technologies, including Skype, the Internet phone service owned by eBay Inc.
"I'm not allowing Skype because I don't know what it does," says Bill Rocholl, global head of strategy and engineering for ABN Amro's telecommunications and network services.
Rocholl says that in making such decisions he weighs whether the resources he needs to study and disarm any potential risks from Skype or other free services would outweigh the time or money that might be saved by using them.
The corporate crackdown underscores an emerging challenge for the Web. As the spread of broadband technology makes it possible for millions of Americans to watch TV on the Web or make cheap phone calls, companies, government agencies and universities are concerned about the possible side effects — including the threat of a worm or other bit of malicious code sneaking into their computer systems.
Some companies worry the new services will overwhelm their networks with unwanted traffic. Others are primarily concerned about security or their ability to track workplace communications, especially in industries like financial services, where regular monitoring is required by regulators. Instant messages from the outside, for example, often aren't logged and archived the way e-mail is, creating a potential backdoor for illicit communications or breaches of client privacy.
Skype and other service providers say such concerns are overblown. They say their products are in many cases safer than e-mail attachments, a common source of viruses that businesses nonetheless consider indispensable tools. They also say the popularity of their services in part reflects their success in weeding out spam, viruses and other nuisances.
Still, many companies are proceeding cautiously.
Global Crossing says it cut off its employees' access to outside instant-messaging services earlier this year after detecting a worm. It now has an internal instant-messaging system from Microsoft Corp., but that system can't be used to reach people outside the company.
Global Crossing started blocking its employees' access to personal e-mail accounts on sites like Yahoo and Time Warner Inc.'s America Online in 2003 after a virus used them to slip in.
"I used to think nothing of checking my Yahoo mail several times a day," says Global Crossing Chief Marketing Officer Anthony Christie. Now that he can't, his long workday makes it hard to avoid using his work e-mail account for personal messages, he says.