User guide

MultiVOIP 400/800 User Guide

You can also set up the DTMF gain (or output level in decibels - dB) for the higher and lower

frequency groups of the DTMF tone pair. Make your selections in the drop-down lists in the

DTMF Gain group.

Note: Only change the DTMF gain under the direction of Multi-Tech Technical Support

supervision.

10. To change the voice coder, first select the channel by clicking the Select Channel down arrow

(highlighting the channel number) then click Manual in the Coder group. To select the appropriate

coder, click the Selected Coder down arrow and highlight your new voice coder entry.

If you changed the voice coder, ensure that the same voice coder is used on the voice/fax

channel you are calling; otherwise, you will always get a busy signal.

Note: If you allow the Coder to be selected automatically, then you need to select the Max

Bandwidth from the drop-down list. Check with your VOIP administrator to determine how much

bandwidth is available.

11. The Fax group enables you to send/receive faxes on the selected voice/fax channel. You can set

the maximum baud rate for faxes and the fax volume in the two drop-down lists and change the

jitter value in milliseconds.

When receiving fax packets from a remote MultiVOIP 400/800, it is possible for individual packets

to be delayed or received out of order due to traffic conditions on the network. To compensate for

this effect, the MultiVOIP 400/800 uses a Jitter Buffer. The Jitter Value field allows the MultiVOIP

400/800 to wait a user-definable period of time, in milliseconds, for delayed or out of order fax

packets. The range of allowable Jitter Values is 0 to 400 with a default of 50 milliseconds.

If you do not plan to send or receive faxes on a given voice/fax channel, you can disable faxes in

the Fax group.

12. You can enable the voice/fax advanced features by clicking (checking) the silence compression,

echo cancellation, or forward error correction options.

The Silence Compression option defines whether silence compression is enabled (checked) for

this voice channel. If silence compression is enabled, the 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.

The Echo Cancellation option defines whether echo cancellation is enabled (checked) for this

voice channel. If echo cancellation is enabled, the MultiVOIP 400/800 will remove echo-delay

which improves the quality of sound.

The Forward Error Correction (FEC) option defines whether forward error correction is enabled

(checked) for this voice channel. The FEC feature allows 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.

Note: After configuring a given channel, you can copy that channel’s configuration by clicking the

Copy button and everything on the Voice/Fax tab will be copied to the designated channel.