Voice/Fax. Multitech MultiVOIP 800 MVP800

MultiVOIP 400/800 User Guide

Voice/Fax

The Voice/Fax tab controls voice and DTMF gain, voice coder, fax settings, and advanced options.

56

The Voice Gain group enables you to select the Input and Output voice gain. Gain is the increased signaling power that occurs as the signal is boosted by the MultiVOIP 400/800. The Input Gain dropdown list defines the input gain for this voice channel. Before your MultiVOIP 400/800 digitizes voice, the volume can be increased or decreased. Input gain modifies the level of the audio coming in to the voice channel before it is sent over the Internet to the remote MultiVOIP 400/800. The valid range for this option is +31dB to –31dB. The recommended and default value is 0. The Output Gain drop-down list defines the voice output gain for this voice channel. Before your MultiVOIP 400/800 converts digital voice back to analog, the volume can be increased or decreased. The output gain modifies the level of the audio being output to the device attached to the voice channel. The valid range for this option is +31dB to –31dB. The recommended and default value is 0.

The DTMF Gain (Dual Tone Multi-Frequency) group controls the volume level of the digital tones sent out for Touchtone dialing. The Gain High and Gain Low fields control the gain in dB (decibels) of the

High and Low tones in the tone pairs; the default gain values are -4 dB and -7 dB, respectively.

DTMF Gain should not be changed except under supervision of MultiTech’s Technical Support.

The MultiVOIP 400/800 supports many state-of-the art ITU (International Telecommunications Union) voice coders. The Voice Coder drop-down menu enables you to select from a range of coders with specific bandwidths. The higher the bps rate, the more bandwidth is used. The channel that you are calling has to have the same voice coder selected; otherwise, you will always get a Busy signal.

The Fax group enables a fax machine to transmit and receive faxes through the MultiVOIP 400/800. If a fax machine is connected to one of the voice/fax channels, the Max Baud Rate should be set to match the baud rate of the fax machine (refer to user documentation). The Fax Volume setting controls the output level of the fax tones, and this setting should be changed only under the direction of Multi-Tech’s Technical Support personnel (see Chapter 6 - Warranty, Service and Tech Support ).

The Jitter Value setting defines the inter-arrival packet deviation (in milliseconds) for the fax transmission. A higher value will increase the amount of delay (allowing for a higher percentage of packets to be reassembled) and a lower value would decrease the amount of delay (a lower percentage of packets would be reassembled).

The Advanced Features group allows you to enable Silence Compression so that a MultiVOIP 400/

800 will not transmit voice packets when silence is detected, thereby reducing the amount of network bandwidth that is being used by the voice channel; Echo Cancellation for a particular voice channel will remove echo and improve the quality of sound; and, Forward Error Correction allowing some of the voice packets that were corrupted (or lost) to be recovered. FEC adds an additional 50% overhead to the total network bandwidth consumed by the voice channel.