Voice over IP systems (VoIP) are built for human speech, so data tones need specific low-distortion 

adjustments to connect properly.


This directly applies to connecting the Viking AES-2000 and its PB-100 programmer to VoIP lines from copper POTS circuits.


The optimum VoIP configuration for analog modem communications requires enabling modem pass-through, 

disabling high-compression codecs, and capping speeds.



Audio and Codec Settings

Use G.711 Codec:

Select the uncompressed G.711 (PCMU/PCMA) codec. 

It offers a clean 64 kbps audio stream without the aggressive digital compression that mangles modem tones.


Disable Silence Suppression: Turn off VAD (Voice Activity Detection) or comfort noise generation so the line stays 

    constantly open during data handshakes.


Turn Off Echo Cancellation: Disable acoustic and line echo cancellation if your ATA (Analog Telephone Adapter) 

    or VoIP gateway has a dedicated "data" or "pass-through" mode.


Modem and Speed Configuration

Enable Pass-Through: Turn on modem pass-through mode on your VoIP gateway rather than T.38 (which is strictly for fax).

Lower Baud Rates: Cap your modem communication speed at 14.4 kbps or a maximum of 33.6 kbps. 

    Never attempt V.90 or V.92 higher rates, as packet jitter will cause disconnects.

Disable Error Correction Adjustments: Let the physical modems handle their own handshakes and error correction over the uncompressed stream.

(the Viking PB-100 only runs at 9600 baud and is not configurable)




To optimize a standalone ATA (Analog Telephone Adapter) for modem communications, 

    you must configure it through its web management interface.


These specific adjustments minimize network jitter and prevent the ATA from distorting the modem's audio tones.


Network and Packet Settings

Lower the Packet Size: Set your Packetization Period (pftime) to 10ms or 20ms to reduce audio delay.


Enable Static Jitter Buffer: Switch the jitter buffer from adaptive to fixed or static.


Set Jitter Buffer to High: Increase the buffer depth to extreme or high to handle network fluctuations.


Codec and Audio Settings

Force G.711u or G.711a: Set both your primary and secondary codecs to G.711 (PCMU in the US, PCMA in Europe).


Disable Silence Suppression: Turn off Silence Suppression or VAD (Voice Activity Detection) completely.


Disable Echo Canceller: Turn Echo Canceller Enable to No.


Advanced Line Configuration:

Set Impedance to 600 Ohms: Ensure your FXS port impedance matches standard analog line levels.


Increase Tx/Rx Gain: Boost audio levels slightly if connections drop during the initial handshake.