(CNN) Nearly half the calls made to US cell phones in 2019 will be spam, according to a study by First Orion referenced in a Federal Communications Commission report Thursday.

Ninety percent of those calls will have familiar caller IDs, but there isn't an effective way of identifying a call as spam before answering.

"Currently, the only certain way to determine whether a call is wanted or unwanted is to answer it or let it go to voicemail, and hope the caller leaves a message," the report said.

Not all robocalls are illegal or unwanted. Businesses such as pharmacies, banks and utility companies use them to provide information and alerts to their customers.

But despite laws prohibiting certain types of robocalls, including those made to individuals on the national Do Not Call Registry and those meant to defraud, such calls have risen over the years.

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