Configuring Dtmf Properties; Configuring Dtmf Detection - 3Com MSR 50 Series Configuration Manual

2260 C 131: V
HAPTER OICE
Configuring DTMF
Properties
n
Configuring DTMF
Detection
S L C
UBSCRIBER INE ONFIGURATION
Figure 655 Key spectrum
As seen from Figure
frequency group, and 697Hz, 770Hz, 852Hz, and 941Hz form a row frequency
group. Each DTMF key tone consists of a row frequency and a column frequency.
For example, the key 1 tone is formed by combining two sine signals of 697Hz and
1209Hz. An effective key tone must last 45 milliseconds at least. There must be a
23-millisecond pause at least between two consecutive key tones. Regulations for
key tone lengths are roughly the same in the world. For details, see ITU Q.24
recommendation.
Follow these steps to configure DTMF properties:
To do...
Enter system view
Enter voice view
Configure the persisting time
and interval for sending DTMF
numbers
Configure a DTMF signal
amplitude
The dtmf time and dtmf amplitude commands in voice view have global
significance. Once you carry out either of the two commands, the configuration
will take effect on the whole device.
Introduction to DTMF
There are two ways to detect DTMF:
Energy detection: DTMF detection is implemented by calculating the frequency
■
spectrum of the input voice signal. The energy threshold limits the spectrum
shape of the input signal. A signal is considered a valid DTMF only when all
requirements are met.
655, 1209Hz, 1336Hz, 1477Hz, and 1633Hz form a column
Use the command...
system-view
voice-setup
dtmf time {interval |
persist } milliseconds
dtmf amplitude value
Remarks
-
-
Optional
By default, both 120
milliseconds.
Optional
-9.0 dBm by default.