Dual-tone multi-frequency signaling ( DTMF ) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center.

Based on this prior success with using MF by specialists to establish long-distance telephone calls, Dual-tone multi-frequency ( DTMF ) signaling was developed for the consumer to signal their own telephone-call's destination telephone number instead of talking to a telephone operator.

The rotary dial was gradually supplanted by Dual-tone multi-frequency pushbutton dialing, introduced at the 1962 World's Fair, which uses a keypad instead of a dial.

A hardware-based IP phone, with Dual-tone multi-frequency signaling | touch-tone dialing.

Dual-tone multi-frequency signaling ( DTMF ), fax transmissions, and high-quality audio cannot be transported reliably with this codec.

When commercial electric power became available, sirens were no longer driven by external sources of compressed air, but by electric motors, which generated the necessary flow of air via a simple centrifugal fan, which was incorporated into the siren ’ s inner cylinder.

As electricity became available, the first fire sirens were manufactured.

Many communities have since deactivated their fire sirens as pagers became available for fire department use.

He later had to spend his days outdoors or in cafés ( where he became friendly with Francis Stuart, whom he had known from Dublin ) so that people could see him if the sirens sounded.

Some species such as sirens and amphiumas have reduced or absent hindlimbs, giving them a more eel-like appearance.

Other locales use the hi-lo signal described above, and some communities ( particularly in New England and northern California ) make use of coded blasts over a diaphone or air horn for fire signals, reserving the use of sirens for more serious situations.

Sirens are not heard on the tape until more than two minutes after what is supposed to be the sound of the shooting ; however, McLain accompanied the motorcade to Parkland Hospital immediately after the shooting, with sirens blaring the entire time.

" As a singer, American audiences know him best for his 1970 Billboard Top 5 " story song " about an Indiana murder fugitive that featured police sirens in the intro and an outro that included more sirens and a police officer warning the fugitive that he was surrounded and to give himself up.

Casualties were lower partly because the sirens had sounded at 11. 45 pm while the Luftwaffe more cautiously attacked from a greater height.

Sirenia, commonly sirenians, are also referred to by the common name sirens, deriving from the sirens of Greek mythology.

The most common tones produced by sirens in the United States are " Alert " ( Steady ) and " Attack "( Wail ).

There is no standard " Fire " signal in the United States, and while the use of sirens by volunteer fire departments is still common, it is diminishing.

In many Midwestern US cities where tornadoes are a common hazard, the emergency sirens are tested regularly at a specified time ( such as, say, noon each Saturday ); while this is not primarily intended as a time signal, locals often do check their watches when they hear it.

Some newer sirens are electronically driven by speakers, though these are not as common.

Other common precautionary measures include the construction of storm cellars, and the installation of tornado sirens.

There was certainly a great deal of activity in the skies over Whitton during the early years of the war with the sound of air raid sirens and anti-aircraft guns very common by both day and night.

Many warning sirens have a sound that is distinct from that used by emergency vehicles due to use of two simultaneous tones, with pitches usually in a 5: 6 frequency ratio ( an untempered minor third ).

Some newer sirens have the ability to broadcast voice messages over large areas, depending on winds and noise.

There is some question about the ability of a system of electronic sirens to broadcast a voice message with sufficient intelligibility over long distances – not only does the sound echo off some surfaces, the sound could have multiple arrival times from widely spaced siren sites.

Authorities have installed a system of lahar sirens throughout the area, activated by sensors on Mt.

However, she remains one of the most iconoclastic women performers in British movie history and certainly one of the most enduringly beautiful and remarkable screen sirens to have ever lived.

Because of this, it is most likely sirens have evolved from a terrestrial ancestor that still had an aquatic larval stage.

The frequent air-raid sirens and explosions of incoming projectiles have caused severe psychological trauma.

This vehicles may have individual revolving lights ( strobes or LEDs ) and / or light bars and sirens.

Younger sirens also have a light stripe along their side, which fades with age.

: The Loeb Library, with its Greek or Latin on one side of the page and its English on the other, came as a gift of freedom ... The existence of the amateur was recognised by the publication of this Library, and to a great extent made respectable ... The difficulty of Greek is not sufficiently dwelt upon, chiefly perhaps because the sirens who lure us to these perilous waters are generally scholars have forgotten ... what those difficulties are.

The speed at which flash floods can arise along this river has resulted in several deaths at the park, and warning sirens have been installed in the park and elsewhere along the river.

By the end of the Cold War, as many as 300 United States citizens were thought to have defected across the Iron Curtain for a variety of reasons – whether to escape criminal charges, for political reasons or because ( as the St. Petersburg Times put it ) " girl-hungry GI's tempted with seductive sirens, who usually desert the love-lorn soldier once he is across the border.

Instead of disks, most modern sirens use two concentric cylinders, which have slots parallel to their length.

In it, the ghost of Grettir speaks with two men, Craven and Ryan, who have been ' hounded ' from a decadent and war-threatened Europe ' whose voice calls in the sirens of destroyers '.

Police vehicles ( except those used by undercover personnel ) traditionally have sirens, loudspeakers, and lightbars that rotate and / or flash.

Even if there had been the space, it would have been impossible to mask the city sounds ( traffic, aeroplanes overhead, Garda Síochána ( police ) sirens, etc .).

Since then, the park and other areas of outdoor gathering in the Nashville area have been equipped with storm-warning sirens.

Models sold as emergency lights have additional functions useful in emergencies, such as flashing red or yellow lights for roadside emergencies, sirens, and AM / FM, weather or shortwave radios.

For patrol duty, 40 Jeeps have been provided equipped with police sirens, revolving lights, public address system, fire extinguisher, top search light, police display light and wireless communication system.

An old tract found in the Book of Lecain states that a king of the Fomorians, when sailing over the Ictean sea, had been enchanted by the music of mermaids until he came within reach of these sirens .... then they tore his limbs asunder and scattered them on the sea.

As sirens are heard, Tom persuades them to leave, emphasizing no one has been hurt.