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Page 344 of 504 Appendix A: Meridian Modular Telephones
553-3001-367 Standard 3.00 August 2005
Local alerting tones
Each telephone provides four alerting tones and a buzz sound. The system
controls the ringing cadence by sending tone-ON and tone-OFF messages to
the telephone. The alerting tone cadences cannot be changed from the
telephone, but can be altered for individual Meridian Modular Telephones by
software controlled adjustments in the system. See Software Input/Output:
Administration (553-3001-311).
All other telephony tones, such as dial tone or overflow, are provided by the
system from a Tone and Digit Switch.
Figure 58
Block diagram of MPDA and Meridian Modular Telephone
553-AAA2135
RS-232-C
DTE I/F
Communications adapter Telephone
CS 1000
/ Meridian 1
EIA
drivers
Receivers
MDAD
A64
uP
MTAC
A44
I
S
D
L
C
D
L
C
or
uP
Power supply
option card
+5V
+12V
Power Supply
-12V
+5V