D-Link DVG-5008SG [38/81] 3 8 fax

DVG-5008SG User’s Manual VoIP Gateway Configuration

D-Link Systems, Inc. 38

3-3-8 FAX

General Settings Ш FAX

Disable - Select it if you are not sending fax, but it is still accepted fax by the VoIP 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 VoIP 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 VoIP

Gateway won’t accept T.38 for fax transmission.

T.38 Native - Select it if you are only using T.38 for fax transmission.

T.30 V.152 – As GW detect FAX tone, it will change RTP codec to be T.30 codec directly without

sending Re-Invite to change codec.

Note: When a fax tone is detected from the call, the VoIP 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.