By Brendan Sasso - 08/02/12 08:13 PM EDT
It is against the law to place unsolicited commercial calls to a cellphone if the call is made using an automated dialing machine or a pre-recorded message.
Earlier this year, the Federal Communications Commission (FCC) adopted rules aimed at cracking down further on robocalling. The commission also banned automated commercial texts by classifying them as "calls" under the law.
Pew emphasized that the study was not intended to measure how many illegal calls consumers are receiving.