AT&T, the company that is being sued by the Electronic Frontier Foundation over its spying on its customers at the behest of Bushco, has a clause in its terms of service that says it will terminate your service if you criticize them.
I wrote this only after making sure we don't have any AT&T accounts. Hey, iPhone owners - talk nice about yer Ma!
Here's the clause:
5.1 Suspension/Termination. Your Service may be suspended or terminated if your payment is past due and such condition continues un-remedied for thirty (30) days. In addition, AT&T may immediately terminate or suspend all or a portion of your Service, any Member ID, electronic mail address, IP address, Universal Resource Locator or domain name used by you, without notice, for conduct that AT&T believes (a) violates the Acceptable Use Policy; (b) constitutes a violation of any law, regulation or tariff (including, without limitation, copyright and intellectual property laws) or a violation of these TOS, or any applicable policies or guidelines, or (c) tends to damage the name or reputation of AT&T, or its parents, affiliates and subsidiaries. Termination or suspension by AT&T of Service also constitutes termination or suspension (as applicable) of your license to use any Software. AT&T may also terminate or suspend your Service if you provide false or inaccurate information that is required for the provision of Service or is necessary to allow AT&T to bill you for Service
So, AT&T can spy on you, but you cannot complain about it! Eat it, little people. The corporate boot is on your neck.