Free Android phone tethering apps found in Android Market are reportedly being blocked by AT&T, Verizon Wireless and T-Mobile.
Sprint continues to support the tethering apps, possibly because it continues to offer unlimited voice, text and data plans.
The other carriers charge $15 to $20 per month to use a smartphone as a portable modem for a tablet or PC. The free tethering apps available in the Android Market, like PdaNet, represent a free or cheap alternative to those charges.
According to Technologizer and other blogs, T-Mobile has long opposed free tethering apps, while Verizon and AT&T have only recently begun the bans.
When users attempt to install tethering apps on the phones of those carriers, they get an on-screen notice that reads, "This item is not available on your carrier."
A spokeswoman at Verizon suggested that any blocking of the free tethering apps is done by Android OS developer Google. However, she wouldn't say whether Google was doing so at the behest of Verizon or the other carriers.
"Google is ultimately responsible for what is in the marketplace," the Verizon spokeswoman said.
Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen, or subscribe to Matt's RSS feed . His e-mail address is email@example.com.