Dtmf Through Dial - Nortel 1000 Description, Installation And Operation Manual

Page 96 of 644 System description

DTMF Through Dial

553-3001-363 Standard 2.00
For applications that send no packets during silence, the first packet after a
silence period is distinguished by setting a marker bit in the Real Time
Protocol (RTP) data header. Applications without Speech Activity Detection
set the bit to zero.
Preservation and transport of tones through the IP Trunk 3.01 (and later)
network is critical for Interactive Voice Response (IVR) services. IP Trunk
3.01 (and later) can be configured to ensure that DTMF tone information is
included in the packets that are sent through the IP Trunk 3.01 (and later)
network and that the tones are re-transmitted by the far-end gateway. The
duration information for DTMF signals is not transmitted; that is, long DTMF
bursts are reduced to a short standard duration.
Callers can access traditional Voice Mail or IVR services (for example,
"Press 1 for more information" or "Press 2 to be connected to our customer
service department"). Services that depend on long DTMF bursts cannot be
accessed.
In order to ensure that DTMF tones are being transmitted properly, the DSP
must be configured correctly in OTM 2.1 (and later). If the IP Trunk 3.01 (and
later) node is configured to use a voice codec other than G.711, "DTMF Tone
Detection" must be selected (checked) in OTM 2.1 (and later). See Figure 21
on page 97. For more information on how to configure the IP Trunk 3.01 (and
later) DSP, see "Configure DSP profiles for the IP Trunk 3.01 (and later)
node" on page 324. If the IP Trunk 3.01 (and later) node is using G.711
without "DTMF Tone Detection" checked, there is no guarantee that DTMF
tones will be properly transmitted to the far end, due to the possibility of
latency or packet loss.
September 2004