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A
DTMF
BOUT
S
ETTINGS
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DTMF
BOUT
Table 3-16
Advanced Settings—General (continued)
Field or Check Box
Support H.239
The SCOPIA Gateway performs Dual Tone Multi-Frequency (DTMF) detection
on IP-to-ISDN calls and on ISDN-to-IP calls. The Gateway can send DTMF tone
information to the IP endpoint in-band only, or both in-band and out-of-band.
The Gateway sends DTMF tone information to the ISDN endpoint in-band only.
Note
For Gateway P20 SP, enabling DTMF detection for video calls reduces the
number of supported calls at 128 Kbps from 30 to 22 when using an E1
connection. Capacities are lower when using a T1 connection
The signal generated by a DTMF encoder is a direct algebraic summation, in real
time, of the amplitudes of time sine (or cosine) waves of different frequencies.
An example of the use of DTMF is in touch tone telephone dialing. DTMF tones
are sent out as you dial. For example, pressing "1" sends a tone created by
combining frequencies of 1209 Hz and 697 Hz.
The touch tone system uses pairs of tones to represent the various keys on the
telephone. A "low tone" and a "high tone" are associated with each button (0-9,
*, and #). The low tones vary according to the horizontal row in which the tone
button is located in
Table
in which the tone is located. The local telephone company receives each pair of
tones, decodes the number dialed and makes the connection.
Description
Select to enable support for dual video channels using the
H.239 protocol. This setting is selected by default.
When selected, the Gateway supports H.239 in ISDN-to-IP
calls and in IP-to-ISDN calls. The Gateway identifies the
protocol version that an IP endpoint uses and sends H.239
capabilities only to those endpoints working with protocol
version 4.0 or later. H.239 support has no impact on
Gateway capacity.
We recommend that you do not enable this feature if you
establish communication with endpoints that do not support
H.245 generic capabilities (endpoints based on H.323
version 2 or earlier) as this might cause the endpoints to fail
upon receiving these capability exchanges.
3-17. The high tones correspond to the vertical column
Configuring the SCOPIA Gateway
Configuring Gateway Settings
117
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