Tadiran Telecom Coral IPx 800 Series, Installation Procedure And Hardware Reference Manual

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Common Control Cards
8-23
HDC C
a
rd
Hig
h
Den
sity Con
tr
o
l
8
3
The HDC card generates the audio call progress tones used to notify the caller of the
status of the call. In addition, tones used during Keyset (FlexSet, GKT, DKT, DST, EKT,
VDK, etc.) ringing (except for mute ring which is a function of the telephone set itself)
dual tone multi-frequency (DTMF) dialing tones, multi-frequency (MFC) dialing tones,
and test tone patterns used by diagnostics are also generated by the 4GC/32GC. These
tones are stored in digital PCM form, in a programmable PROM. The stored tone
patterns are output directly to the digital PCM bus when required.
Two methods of encoding audio sounds into a digital, PCM form are in common use:
„
The A-Law method is in common use throughout Europe, Africa, Asia, South
America, and many countries in other continents.
„
The
µ
-Law (pronounced M-YOO Law, sometimes spelled Mu-Law, or m-Law)
method is in common use in North America. Neither method has any particular
advantage over the other.
The Coral switching system may operate using either encoding method. The database
defaults are set to the
µ
-Law (m-Law) method for systems shipped to North America,
and A-Law for all other locations. For instructions on the database programming, see
the Program Interface and Database Reference Manual- Chapter 6 System Features (Tones,
Route: SFE, 8, M_LAW).
To operate a system using the non-default encoding method, the database must be
programmed appropriately, and the tone PROM located on the HDC card must be
changed to PROM containing the system tones stored in the appropriate encoding
method.
The encoding method is important only when the Coral system interfaces with another
switching system through a digital trunk interface card such as a T1, 30T, 30T/x, 4TBR,
8TBR, PRI-23 or PRI-30. In this case, the encoding method of both systems must match,
so that audio signals encoded by one system can be properly decoded by the other.
The integrated circuit socket U45 includes the tone PROM. See
Figure 8-4.
This PROM
contains DTMF and MFC dialing tones and other system tones such as dial tone,
ringback tone, busy tone, the Keyset ringing tones. The tone PROM present in the
HDC card IC socket varies according to the country of use. The correct tone PROM for
each country of use is supplied by the manufacturer.
3 Tone PROM