Nortel RLC Installation And Administration Manual page 196

Configuring the RLC
Dialtone/DTMF Relay
Dialtone/DTMF Relay allows you to manage the bandwidth used by your
Remote Gateway 9100 Series units for generating dial tone and Dual Tone
Multi-Frequency (DTMF), or button-press, tones. With Dialtone/DTMF Relay
enabled, Remote Gateway 9100 Series units send encoded data packets to the
other side when they detect either dial tone or DTMF tones. With Dialtone/
DTMF Relay disabled, the units send voice packets to the other side when they
detect a dial tone or DTMF tones. The former method uses less bandwidth, but
produces rougher DTMF tones and a dial tone that begins with an audible click.
The latter method produces smoother DTMF tones and dial tone, but uses more
bandwidth.
NLP
The non-linear processor (NLP) works with the Remote Gateway 9100 Series
echo canceller to reduce echo. Echo occurs in a telephone call when the
transmitted signal reflects and is received by the transmitting device. To cancel
the echo, the Remote Gateway 9100 Series system monitors the audio stream
looking for echo. When echo is identified it is digitally (mathematically)
removed. If the echo is very strong, a small amount of echo may remain called
"residual" echo. The aggressiveness of the NLP determines how quickly and
how effectively the Remote Gateway 9100 Series NLP reduces the residual
echo.
The operation of the NLP can affect how the audio sounds during double-talk
situations - when both parties are speaking. Cultural differences also changes
how often double-talk occurs during a conversation.
Nortel recommends the following settings as a starting point:
RLC: NLP Enabled - Less Aggressive (default)
9150: NLP Enabled - More Aggressive (default)
If the Remote Gateway 9150 unit user hears echo during conversations, adjust
the settings, as follows:
RLC: NLP Enabled - More Aggressive
9150: NLP Enabled - Less Aggressive
170 RLC Installation and Administration Guide
Standard 4.0