The non-emergency 101 number for police has been rolled out to all forces across England and Wales as an alternative to 999.
Policing Minister Nick Herbert said the move was one of the most significant changes in the way people contact the police since 999 was brought in nearly 70 years ago.
Designed for crimes and concerns that do not require an emergency response, the 101 number has already received 2.5 million calls while it has been being phased in.
Only one in four calls to 999 require an emergency response and the new number is expected to ease pressure on 999 call handlers, enabling police to respond to genuine emergencies more effectively.
Commander Ian Dyson, of the Association of Chief Police Officers (Acpo), said: "Having just two phone numbers - 101 for reporting a crime that has happened, to get advice or to raise local policing issues - or 999 if it's an emergency, makes calling the police a lot easier and makes our services more accessible.
"999 should only be used in an emergency, that is when a crime is happening, when someone suspected of a crime is nearby, or where someone is injured, being threatened or in danger.
"For all other matters the public should call us on 101."
Calls to 101 cost 15p from both mobile phones and landlines, regardless of how long the call is or when it is made.