(CBS) – Federal authorities have filed a series of lawsuits against individuals and companies responsible for sending out unsolicited text messages offering free gift cards to popular stores.

WBBM Newsradio’s Bernie Tafoya reports the federal government estimated at least 180 million spam text messages have been sent to cell phones nationwide.

The Federal Trade Commission has sued 29 people and companies responsible for sending spam texts.

“In some cases, we’re seeing individual telephone numbers sending 100,000 texts a day,” FTC staff attorney Steve Wernikoff said.

The messages end up costing the people who get them for text message charges, as well as shipping and handling costs if they accept one of the offers. People who respond can also become victims of other scams when they send out their personal information.

“Collectively, we think that these spam text messages involved in this case have cost consumers millions of dollars,” said FTC Midwest Region Director Steve Baker.

Baker said the FTC can’t tell know if consumers ever receive a gift card after responding to such offers.

“Does anyone ever get a gift card? Well, we don’t know for sure yet, because most consumers give up long before they’ve jumped through all the required hoops,” Baker said.

If you receive a spam text, you can report it by forwarding the message to 7726. That’s a center operated by telephone companies to try to track down and block the numbers being used by spam texters.

“The moral’s the same on all these things: don’t click on any links. Do delete them, do report them,” Baker said.

So far, there’s no “do not text” list similar to the “do not call” list.