The Federal Communications Commission voted Thursday to regulate the Internet in a decision that is likely to trigger lawsuits from big Internet service providers Comcast, AT&T, Verizon and others.

Internet service providers would have to act in the “public interest” when providing a mobile connection to your home or phone, under rules the FCC approved 3-2.

The vote was the second defeat of the day for cable providers. Earlier, the FCC voted to allow Wilson and Chattanooga, Tenn., to expand services sold through their municipal-owned networks. North Carolina and Tennessee both had passed laws seeking to limit municipal broadband efforts.

The “net neutrality” rules put the Internet in the same regulatory camp as the telephone, banning providers from “unjust or unreasonable” business practices.

The FCC vote is considered a victory for consumer advocates and companies such as Netflix and Twitter that have long warned that some providers want to create paid “fast lanes” on the Internet, edging out cash-strapped startups and smaller Internet-based businesses.

The broadband industry is expected to sue, arguing that the plan constitutes dangerous overreach. Republicans in Congress said they will try to pass legislation scrapping the rules, although it’s unlikely that such a bill would be signed into law by President Barack Obama.

“One way or another, I am committed to moving a legislative solution, preferably bipartisan, to stop monopoly-era phone regulations that harm Internet consumers and innovation,” Republican U.S. Sen. John Thune of South Dakota, chairman of the Senate Commerce Committee, said in a statement this week.

Twitter said the new rules were a matter of protecting free expression.

“Safeguarding the historic open architecture of the Internet and the ability for all users to ‘innovate without permission’ is critical to American economic aspirations and our nation’s global competitiveness,” Twitter wrote in a company blog post this week.

Net neutrality is the idea that all websites or videos load at about the same speed. That means someone won’t be more inclined to watch a particular show on Amazon Prime instead of on Netflix because Amazon has struck a deal with the local service provider to load its data faster.

For years, providers mostly agreed not to pick winners and losers among Web traffic because they didn’t want to encourage regulators to step in and because they said consumers demanded it. But that started to change around 2005, when YouTube came online and Netflix became increasingly popular. On-demand video became known as data hogs, and evidence began to surface that some providers were manipulating traffic without telling consumers.

By 2010, the FCC enacted open Internet rules, but the agency’s legal approach was eventually struck down. FCC officials are hoping to erase the legal ambiguity by no longer classifying the Internet as an “information service” but a “telecommunications service” subject to Title II of the 1934 Communications Act.

That would dramatically expand regulators’ power over the industry by requiring providers to act in the public’s interest and enabling the FCC to fine companies found to be employing “unreasonable” business practices.

The FCC says it won’t apply some sections of Title II, including price controls. That means rates charged to customers for Internet access won’t be subject to preapproval. But the law allows the government to investigate if consumers complain that costs are unfair.