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UC-P100-S/UC-P110-S Phones for Skype for Business
Supplemental Guide – DOC. 8412A
DTMF
DTMF is the signal sent from the phone to the network, generated when pressing the
phone’s keypad during a call. Each key pressed on the phone generates a tone comprised
of two frequencies: a high frequency and a low frequency.
The DTMF keypad is laid out in a 4×4 matrix, with each row representing a low
frequency, and each column representing a high frequency. Pressing a digit key (such as
'1') will generate a tone for each of two frequencies (697 and 1209 hertz (Hz)).
DTMF Keypad Frequencies
1209 Hz
1336 Hz
1477 Hz
1633 Hz
697 Hz
1
2
3
A
770 Hz
4
5
6
B
852 Hz
7
8
9
C
941 Hz
*
0
#
D
Methods of Transmitting a DTMF Digit
DTMF digits are transmitted by RTP Events compliant with RFC 2833. The payload type
and sending times of the end RTP Event packet can be configured. The RTP Event packet
contains 4 bytes. The 4 bytes are distributed over several fields denoted as Event, End
bit, R-bit, Volume and Duration. If the End bit is set to 1, the packet contains the end of
the DTMF event. The sending times of the end RTP Event packet can be configured.
Configuration changes can be performed using the configuration files or locally.
Configuration Methods
Central Provisioning
(Configuration File)
<y0000000000xx>.cfg
Configure the number of times for the
phone to send the end RTP Event packet.
Parameter:
features.dtmf.repetition
Local
Web User Interface
Configure the number of times for the
phone to send the end RTP Event packet.
Navigate to:
http://<phoneIPAddress>/servlet?p=feat
ures-general&q=load