Americans received 26.3 billion robocalls on their mobile phones in 2018, according to Hiya. That was 46 percent more than in 2017. Consumers received an average of 10 spam calls per month, Hiya found. The top unwanted call in the U.S. was for the Wangiri, or “one-ring” scam, which grew 250 percent year over year. Seven of the top area codes targeted by spammers were in Texas. Robocalls purporting to be from debt collectors made up 15 of the top 20 toll-free numbers used. The remaining five were used by telemarketers.