Yealink SIP-T46G Administrator's Guide

Configuring Basic Features
105
DTMF (Dual Tone Multi-frequency), better known as touch-tone, is used for
telecommunication signaling over analog telephone lines in the voice-frequency band.
DTMF is the signal sent from the IP phone to the network, which is generated when
pressing the IP phone’s keypad during a call. Each key press on the IP phone generates
one sinusoidal tone of two frequencies. One is generated from a high frequency group
and the other from a low frequency group.
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 sinusoidal tone for each of two frequencies (697 and 1209 hertz
(Hz)).
DTMF Keypad Frequencies:
1209 Hz
1336 Hz
1447 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
There are 3 common methods of transmitting DTMF digits on SIP calls:
 RFC 2833 – DTMF digits are transmitted by RTP Events compliant to RFC 2833.
 INBAND – DTMF digits are transmitted in the voice band.
 SIP INFO – DTMF digits are transmitted by the SIP INFO messages.
The method of transmitting DTMF digits is configurable on a per-account basis.
RFC 2833
DTMF digits are transmitted using the RTP Event packets that are sent along with the
voice path. These packets use RFC 2833 format and must have a payload type that
matches what the other end is listening for. The payload type for the RTP Event packets
is configurable. IP phones default to 101 for the payload type, which use the definition to
negotiate with the other end during call establishment.
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. You can configure the number of times the IP
phone sends the RTP Event packet with End bit set to 1.
INBAND
DTMF digits are transmitted within the audio of the IP phone conversation. It uses the

Yealink SIP-T46G Specifications

General

Backlight	Yes
Power requirements	100-240V, DC 5V
Touchscreen	-
Display diagonal	4.3 \
Display resolution	480 x 272 pixels
Lines quantity	- lines
Phonebook capacity	1000 entries
Number of VoIP accounts	6
Voice codecs	G.711, G.722, G.723, G.726, G.729A, G.729B
Bluetooth	No
RJ-9 ports quantity	2
USB 2.0 ports quantity	USB 2.0 ports have a data transmission speed of 480 Mbps, and are backwards compatible with USB 1.1 ports. You can connect all kinds of peripheral devices to them.
Ethernet LAN (RJ-45) ports	1
Storage temperature (T-T)	-10 - 50 °C
Operating relative humidity (H-H)	10 - 95 %
Handset type	Wired handset
Product type	IP Phone
Product color	Black
Number of handles included	1 pc(s)

Weight and Dimensions

Depth	185 mm
Width	244 mm
Height	213 mm