Calling the Target as An Investigative Tactic:
Imagine you're a police detective and you're investigating a suspect who has not yet been charged. Why not call the suspect at home (or on his cell phone), explain the allegations against him, and politely ask him to respond?

  If the suspect is really smart, he'll refuse to speak. But as we know from the Miranda context, a lot of suspects won't be smart: I would guess that a lot of suspects would confess at least in part. The call won't trigger Miranda because the suspect obviously is not in custody; and it won't violate the Sixth Amendment because no charges have been filed. Plus it's cheap and easy, and its informality may make suspects more willing to talk. Why not try it? (I'm assuming the suspect already knows he is under investigation or else the police don't mind informing him of it.)

  Okay, now let's change hats. Imagine you're a legislator rather than a police detective. Would you support a law prohibiting law enforcement officers from calling suspects on the phone in an effort to get them to make incriminating statements?