D-Link DVG-5402SP User Manual page 39

DVG-5402SP User's Manual
3-2-1-8 Fax
ADVANCED → VoIP → FAX
Disable - Select it if you are not sending fax, but it is still accepted fax by the VoIP Router.
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 VoIP Router 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 VoIP
Router 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 VoIP Router 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.
D-Link Systems, Inc.
39
ADVANCED