Configuring Automatic Gain Control (Agc) - AudioCodes Mediant 1000 User Manual

3. Upon detection of the end of voice (i.e., end of the greeting message of the answering
machine), the device sends the Application server the following:
INFO sip:sipp@172.22.2.9:5060 SIP/2.0
Via: SIP/2.0/UDP 172.22.168.249;branch=z9hG4bKac482466515
Max-Forwards: 70
From: sut <sip:3000@172.22.168.249:5060>;tag=1c419779142
To: sipp <sip:sipp@172.22.2.9:5060>;tag=1
Call-ID: 1-29753@172.22.2.9
CSeq: 1 INFO
Contact: <sip:56700@172.22.168.249>
Supported: em,timer,replaces,path,resource-priority
Allow:
REGISTER,OPTIONS,INVITE,ACK,CANCEL,BYE,NOTIFY,PRACK,REFER,INFO,SUB
SCRIBE,UPDATE
User-Agent: Audiocodes-Sip-Gateway/v.6.40A.040.004
Content-Type: application/x-detect
Content-Length: 34
Type= PTT
SubType= SPEECH-END
4. The Application server now sends its message to the answering message.
If the device detects voice and not an answering machine, the SIP INFO message
includes:
Type= AMD
SubType= VOICE
If the device detects silence, the SIP INFO message includes the SubType SILENT.

12.4.2 Configuring Automatic Gain Control (AGC)

Automatic Gain Control (AGC) adjusts the energy of the output signal to a required level
(volume). This feature compensates for near-far gain differences. AGC estimates the
energy of the incoming signal (from the IP or PSTN, determined by the parameter
AGCRedirection), calculates the essential gain, and then performs amplification. Feedback
ensures that the output signal is not clipped. You can define the required Gain Slope in
decibels per second (using the parameter AGCGainSlop) and the required signal energy
threshold (using the parameter AGCTargetEnergy).
When the AGC first detects an incoming signal, it begins operating in Fast Mode, which
allows the AGC to adapt quickly when a conversation starts. This means that the Gain
Slope is 8 dB/sec for the first 1.5 seconds. After this period, the Gain Slope is changed to
the user-defined value. You can disable or enable the AGC's Fast Mode feature, using the
ini file parameter AGCDisableFastAdaptation. After Fast Mode is used, the signal should
be off for two minutes in order to have the feature turned on again.
Note:
SIP User's Manual
The AGC feature requires that the device be installed with the IP Media
Detectors Feature Key
164
Mediant 600 & Mediant 1000
Document #: LTRT-83310