Editing Dial tone (section)

==Variants==
===Second dial tone===
[[Private branch exchange]]s (PBXs) or [[key telephone system]]s also play a dial tone to station users. It may be the same type as used by the [[public switched telephone network]] (PSTN), or it may be a different tone to remind users to dial a prefix or select by another method an outside line.

===Secondary dial tone===
A secondary dial tone is a dial tone-like sound presented to the caller after a call has been set up to prompt for additional digits to be dialed. Secondary dial tones are often used in call queuing and call forwarding systems.

===Stutter dial tone===
A stutter dial tone is a rapidly interrupted tone used to indicate special service conditions. It may serve as a [[message-waiting indicator]] for voice mail, or indicate that a [[calling feature]], such as [[call forwarding]] has been activated.

===Soft dial tones===
A soft dial tone or express dial tone may be used when no actual service is active on a line, and normal calls cannot be made. It is maintained only so that an attached phone can dial the [[emergency telephone number]] (such as [[9-1-1|911]], [[112 (emergency telephone number)|112]] or [[999 (emergency telephone number)|999]]), in compliance with the law in most places. It can sometimes also call the business office of the [[local exchange carrier]] which owns or last leased the line, such as via [[6-1-1]]. Other functions such as [[ringback number|ringback]] or [[Automatic number announcement circuit|ANAC]] may also be accessed by technicians in order to facilitate installation or activation.