• by Wendy Davis  @wendyndavis, February 4, 2010

Cable company Cox Communications has sued CenturyLink for allegedly making false and misleading claims in its broadband ads.

In a papers filed with the U.S. District Court in Nevada, Cox complains about several specific TV and radio ads that compare its broadband services to those offered by CenturyLink (formed by a merger of Embarq and CenturyTel).

"Unlike Cox, it's consistently fast no matter how many people are online," one CenturyLink ad allegedly says. Cox argues that this ad conveys the wrong impression that its service is not consistently fast.

Another CenturyLink ad allegedly highlights that its DSL connections are "100% yours, 100% of the time." Cox asserts that this language "creates the false and misleading impression that CenturyLink provides its customers with a dedicated connection to the Internet that is never shared."

CenturyLink said it intends to "fully and vigorously" defend itself. "CenturyLink is confident that its advertising complies with all applicable practices and laws," the company said in a statement.

Cox declined to comment beyond what it alleged in its complaint.

Ad disputes between service providers have landed in court before, and are often resolved without a full-blown trial. Last year, AT&T sued Verizon for running ads that showed it has five times more 3G coverage than AT&T. That case was settled after a judge denied AT&T's request for an injunction banning Verizon from airing the ads.

In general, customers connecting to the Web through DSL lines tend to have consistent speeds regardless of how many other people are also online because DSL customers don't share the "last mile" of wires connecting to the Web, says Chris Riley, policy counsel at broadband advocacy group Free Press.

At the same time, cable modems tend to offer faster maximum speeds, but subscribers' actual speeds can depend on how many other consumers are connecting at the same time.

Riley adds that these types of individual lawsuits don't address the fundamental problem that ISPs' advertised speeds often differ from the real-world speeds experienced by customers. "The right solution here is not a bunch of individual lawsuits, but rules from the FCC to require disclosure of actual speeds."