User Manual

DVG-G5402SP User’s Manual ADVANCED
D-Link Systems, Inc. 48
2-2-3-8 Fax Settings
ADVANCED → VoIP → FAX SETTINGS
Fax / Modem: Select the appropriate type for fax detection by the gateway.
Disable - Select it if you are not sending fax, but it is still accepted fax by the gateway.
T.38 Fax - Select it if you are using T.38 as the protocol for fax transmission. T.38 is used for reliable
and efficient facsimile transmission over network. It transmits and receives FAX waveform (relaying)
over the codec negotiated during call setup this bandwidth consumed is lowered. T.38 protocol also
supports redundancy to get better FAX quality.
T.30 Fax - Select it if you are using T.30 as the protocol for fax transmission. It transmit FAX signal as
voice thus uncompressed G.711 would be the choice. (G.726 also works but not recommended). Due
to this nature, T.30 always requires a SDP change (change of codec within a session, SIP Re-Invite
required) after FAX tone detected by the callee. It will consume more network resources and will affect
transmission quality. The gateway is still able to change the protocol from T.38 to T.30 if the called
party uses T.38 for fax transmission.
T.30 Fax/Modem - Select it if you use it as the protocol for transmission of fax/modem over IP
network.
T.30 Only - Select it if you are using G.711 a-law or G.711 u-law for fax transmission. The gateway
won’t accept T.38 for fax transmission.
T.38 Native - Select it if you are only using T.38 for fax transmission.
Note: When a fax tone is detected from the call, the gateway will automatically switch from voice mode to
fax mode. Hence, the fax settings will be temporarily applied to a specific port which detects the fax tones,
instead of its default voice settings.
ADVANCED → VoIP → FAX SETTINGS
Enable High Quality: Check the box to increase approximately two times the bandwidth in order to
compensate possible loss of packet during transmission and offers a better and reliable fax quality.
FAX Codec: Select G.711 a-law, G.711 u-law, or G.726 for T.30 from the drop-down menu.
FAX Jitter Buffer: Enter the buffer or jitter when receiving packets.
Note: When you send a fax over an IP network, the IP network needs to support fax over IP functionality
(either T.38 or T.30). Please consult your VoIP service provider for this setting.