It's called an off hook tone. Or you can call it a receiver off hook tone or r.o.h. tone or a permanent signal.
In telephony, the "thing" the receiver is placed upon after hanging up is called the "hook" because on the old wall phones it literally was a hook. If you neglect to hang up a phone, it is said to be "off hook" and this condition can be detected at the central phone switch. Likewise, a phone properly stowed and inactive is said to be "on hook". Even though we no longer stow our phone receivers on a hook, the terms "on hook" and "off hook" are still used in the telephone business.
An off-hook circuit refers to the state in which a telephone handset is lifted from its cradle, indicating that the line is engaged in a call. When the handset is off-hook, the circuit is closed, allowing communication to take place.
it has 52volt dc off hook
technologies that are used in telephone exchange include manual service, dial service, telephone exchange and telephone switch. Other services include concentrator, off-hook, on-hook and wire center.
Off the hook probably came from fishing, where you release fish that you aren't keeping--take them off the hook and let them go back into the water. There is also "ringing off the hook," referring to a lengthily unanswered telephone. The receivers of early telephones hung from a hook.
It should hear it beeping which is an alarm to let you know that your phone is off the hook. I think it is a so called permanent signal.
Run the audio through a receiver and speakers. Most receivers will let you hook up headphones and the speakers can either be on or off.
Off the hook means - freed from danger or blame or obligation; "I let him off the hook with a severe reprimand"
The duration of Guy Off the Hook is 1800.0 seconds.
Guy Off the Hook was created on 2008-09-14.
The technical name for the off hook tone for the AT&T Phillips Tel 5ESS-PBX host is not stated. It is stated that there were several Tennessee telephone company offices that had a switched to the type ATT/Philips Tel 5ESS-PBX host.