Who I have the same questioned this topic

My iPhone 6s has been showing many calls from unknown numbers among the list of recent calls. The phone does not ring when these calls come in, even though the ringer is at full volume, the silencer button is not engaged, and I have the phone next to me, so these calls are listed as missed calls. No voicemails are registered. Are these robocalls that Verizon is blocking? This began around the first of February.