Text 43953, 60 rader
Skriven 2008-03-01 08:51:00 av TOM WALKER (1:123/140)
     Kommentar till en text av JAMES BRADLEY
Ärende: Princess.
=================
JB> TW> Here are the DTMF Tone Frequencies, IF they don't get messed up in
JB> TW> transmission

JB>         TW> 1209hz    1336hz    1477hz    1633hz
JB> TW> 697hz         1         2         3         A
JB> TW> 770hz         4         5         6         B
JB> TW> 852hz         7         8         9         C
JB> TW> 941hz         *         0         #         D

JB>...Just messed up when I quoted it. But, what's with the "ABCD"? I don't see
JB>those keys on any of my phones.


Here is the Scop on thge Special keys. They never appeared on
Standardhome phones as far as I know. But the system stil can use those
tome Combinations.

#, *, A, B, C, and D

The engineers had envisioned phones being used to access computers, and
surveyed a number of companies to see what they would need for this
role. This led to the addition of the number sign (#) and star (*) keys
(also known as humphries),[citation needed] as well as a group of keys
for menu selection: A, B, C and D. In the end, the lettered keys were
dropped from most phones, and it was many years before the humphries
became widely used for vertical service codes such as *67 in the United
States and Canada to suppress caller ID.

Public payphones that accept credit cards use these additional codes to
send the information from the magnetic strip.

The U.S. military also used the letters, relabeled, in their now defunct
Autovon phone system. Here they were used before dialing the phone in
order to give some calls priority, cutting in over existing calls if
need be. The idea was to allow important traffic to get through every
time. The levels of priority available were Flash Override (A), Flash
(B), Immediate (C), and Priority (D), with Flash Override being the
highest priority. Pressing one of these keys gave your call priority,
overriding other conversations on the network. Pressing C, Immediate,
before dialing would make the switch first look for any free lines, and
if all lines were in use, it would disconnect any non-priority calls,
and then any priority calls. Flash Override will kick every other call
off the trunks between the origin and destination. Consequently, it is
limited to the White House Communications Agency. Precedence dialing is
still done on the military phone networks, but using number combinations
(Example:Entering 93 before a number is a priority call) rather than the
separate tones.
Audio sample:

Present-day uses of the A, B, C and D keys on telephone networks are
few, and exclusive to network control. For example, the A key is used on
some networks to cycle through different carriers at will (thereby
listening in on calls). Their use is probably prohibited by most
carriers. The A, B, C and D tones also have been used in amateur radio
phone patch and repeater operations to allow, among other uses, control
of the repeater while connected to an active phone line.

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 þ SLMR 2.1a þ Typo Tom strikes agaoin
 * Origin: Doc's Place BBS Fido Since 1991 docsplace.tzo.com (1:123/140)