FCC Democrats portrayed the effort as a pro-competitive measure that will protect consumers and help spread mobile broadband access across the country.
"The framework we adopt today will spur investment in mobile broadband and spur competition," FCC Chairman Julius Genachowski said.
The effort allows the FCC to deliver on a top request from midsize carriers such as Sprint as well as smaller carriers who do not offer service nationwide.
Genachowski noted that every commenter who filed in this proceeding, other than Verizon and AT&T, asked the FCC to regulate in this area.
Doing otherwise would amount to "shirking our responsibilities," he said.
Proponents say the new rules are necessary due to the dearth of data roaming agreements between Verizon, AT&T and smaller carriers.
Consolidation in the wireless industry makes the rules more important than ever, supporters said at the FCC's meeting on Thursday.
The rules passed over strong objections from Republicans. They said the mandate exceeds the authority of the FCC.
"We cannot evade the law," said GOP Commissioner Robert McDowell, adding that the decision runs counter to congressional intent.
Voice roaming agreements are already mandatory. The Republican commissioners said regulating data services is out of bounds, however, because data services are governed by a less stringent part of the Communications Act.
The Republicans said the rules will subject companies to "common carrier" regulations, while hurting the spread of broadband.
"Artificially low roaming rates could create disincentives for carriers to build their next tower," Republican Commissioner Meredith Attwell Baker said.
FCC general counsel Austin Schlick argued that the rules do not constitute a common carriage requirement because providers maintain the flexibility to shape their agreements.
"This is the very opposite of common carriage," Genachowski said.
AT&T and Verizon say they do enter into contracts with small carriers, so government intervention is unnecessary. Verizon has suggested it may take the FCC to court on this issue.
Verizon's top policy executive Tom Tauke said in a statement reacting to the vote: "Today’s action represents a new level of unwarranted government intervention in the wireless marketplace. By forcing carriers that have invested in wireless infrastructure to make those networks available to competitors that avoid this investment, at a price ultimately determined by the FCC, today’s order discourages network investment in less profitable areas. That is directly contrary to the interests of rural America and the development of facilities-based competition and potential job creation. Therefore, it is a defeat for both consumers and the innovation fostered by true competition."
Sprint executive Vonya McCann cited AT&T's merger with T-Mobile as she commended the FCC for taking action.
"The FCC must be congratulated for taking this action despite the opposition of the two largest U.S. wireless carriers who have lobbied against this pro-consumer, pro-competitive item. With AT&T’s proposed acquisition of T-Mobile and the corresponding threat it poses to continued wireless competition, it is absolutely critical that the FCC take steps to promote competition and level the playing field," she said.
Small wireless carriers also praised the decision.
"The watershed decision to adopt automatic data roaming will bring significant benefits to consumers, spur innovation and will promote competition in the wireless industry. We are very pleased with the FCC's decision, which certainly will be viewed as historically significant," said Rural Cellular Association President Steven Berry.