PORT CHARLOTTE, Fla. John Corso’s number keeps showing up on other people’s caller IDs. But he’s not the one calling. “They call me back, and I’m getting anywhere from 10 to 20 calls a day,” the Port Charlotte contractor said. Corso and his wife, Sheryl, contacted their phone company to see what could be done. But they were told there wasn’t much they could do, aside from changing their phone number. But a new phone number could negatively affect their business, since so many clients have their existing number. “We already have advertisements out,” Sheryl Corso said. “It’s listed places. It’s not that easy to change without impacting the business.” The problem the Corsos face is because of caller ID “spoofing,” which is what happens someone tricks the caller ID system into thinking a call is coming from one number when it’s actually coming from another. As long as no harm is intended or caused, spoofing is technically legal, according to the FCC. It’s only considered illegal if a misleading or inaccurate caller ID is used with the intent to defraud, cause harm or wrongly obtain anything of value. The Corsos aren’t sure how or why they became spoofing targets and plan to wait to see if the problem goes away as people “catch onto the trick,” John Corso said. Security experts warn against sharing your phone number online in contests or on forms. Doing so leaves you open to spoofing.