By a 5-0 vote, the FCC said sending to cell phones or handheld computers would not be permitted unless the recipient had asked to receive the correspondence.
But the FCC's decision not to includesent through mechanisms like SMS--short message service--has the potential to create a regulatory loophole. Wireless providers often charge a few pennies per text message received.
Verizon Wireless subscribers exchanged 2.3 billion text messages last quarter, up from 2.1 billion during the previous quarter. Cingular Wireless reported 1.4 billion text messages sent during its last quarter.
The FCC has previously said that it believes unsolicited SMS messages are restricted by the 1991 "junk fax" law called the Telephone Consumer Protection Act. The TCPA, however, only bans automated dialers from "calling" phone numbers, which may not cover SMS messages that are transmitted digitally.
"The commission found that Short Message Service messages transmitted solely to phone numbers, as opposed to those sent to addresses with references to Internet domains, are not covered by these protections," the FCC said in a statement after the vote.
Under the Can-Spam Act, the FCC had until late August to publish regulations prohibiting "mobile service commercial messages unless the subscriber has provided express prior authorization to the sender," a broad definition that seems to include text messages. But the law also gave the FCC the authority to shrink that definition when necessary to address "unique technical aspects" of different forms of wireless communications.
The FCC's rules permit mobile providers to register their Internet domain names in a master database that spammers are supposed to honor. That database will include only domain names like attwireless.com and t-mobileusa.com, and not individual e-mail addresses of subscribers.
"Spam has become the plague of the information age," FCC Chairman Michael Powell said at Wednesday's public meeting. "It truly frustrates, if not destroys, the powerful experience that some of the new technologies can provide."
Noncommercial messages sent by politicians, nonprofit groups or charities are not covered by the Can-Spam Act or the FCC's forthcoming rules. Anyone violating those rules by sending spam to a mobile device can be sued in civil court by the Federal Trade Commission. The text of the final regulations, however, has not been released.
CNET News.com's Ben Charny contributed to this report