Batphone

The Batphone is a very important piece of technology in the Batman franchise.

It is a a form of communication between Batman and Commissioner Gordon and is used to contact him and Robin if he needs their help.

Comics
The Batphone only appeared as an unnamed object in Detective Comics  being used by Commissioner Gordon to contact the Dynamic Duo.

Batman 1960s series and movie
The Batphone was frequently used in the series. Whenever a sinister arch-criminal that the Police Department cannot handle, Commissioner Gordon uses it to contact Batman and Robin asking for their help.

Because the phone number is unlisted, a black button is in the center of the dial area which, when pushed, connects Commissioner Gordon to Batman or visa versa. It gives a beeping sound and it flashes when it is in use.

Three of the original phones are seen in Commissioner Gordon's office, Bruce Wayne's study and the Batcave. There are also different versions that are wired to hook ups in Batman's vehicles, utility belt and weapons. Alfred is usually the first to answer the phone that is heard in Bruce Wayne's study and immediately tells Bruce and Dick that the Commissioner has called whilst also trying not to make Dick's Aunt Harriet suspicious, although once she did comment to Alfred that she found the noise coming from the study annoying.

After being told by Alfred, Bruce and Dick head for the study to answer it where Commissioner Gordon tells them how they can help, though it is sometimes used by Batgirl to help them or by some criminal to mock them.

In the Batcave, the same purpose for the phone is used, with Batman usually giving the Commissioner and Chief O'Hara instructions on what to do next or the Commissioner giving the Dynamic Duo more information

If any call from the Batphone is being traced, an automatic alarm is sounded and Batman can block the signal and divert it with the diversionary Batline equipment.

The Adventures of Batman/The New Adventures of Batman
In the two animated shows, the Batphone retained it's original colour with a few changes: it was only seen in the Batcave and had the Batlogo. One was seen on the Batcomputer that had no dialing butoons, but on a table, it had dialling buttons.