When will a police officer administer a Miranda warning to a suspect?

Any interview of one suspected of a crime by a police officer will have coercive aspects to it, simply by virtue of the fact that the police officer is part of a law enforcement system which may ultimately cause the suspect to be charged with a crime. But police officers are not required to administer Miranda warnings to everyone whom they question.... Miranda warnings are required only where there has been such a restriction on a person's freedom as to render him "in custody." It was that sort of coercive environment to which Miranda by its terms was applicable, and to which it is limited.

See also Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694: