The bill was part of what Davis called a package of "leave-us-alone legislation."
"We have a little home office, and I'm constantly getting unwanted ads there," Davis said last week after signing the bill.
The bill's author, Assemblyman Tim Leslie, R-Tahoe City, said the bill will stop spam text messages from getting as out of control as spam e-mail.
Other bills included in the package will ban unsolicited faxed advertisements and changes to the state's do-not-call list for telemarketers.
The laws go into effect in January.
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