When sending/receiving faxes via ISDN CAPI 2.0, Fax Voip T.38 Modem does not use fax features of your ISDN card, as it is usually done in the CAPI 2.0 fax applications. Fax is transmitted as standard audio data. Fax Voip T.38 Modem operates the same way like analog fax machine that connected to the ISDN line via adapter. Fax Voip T.38 Modem uses the same technology that is used when transmitting audio faxes via SIP or H.323 (Fax over G.711 codec). Possibility to use CAPI 2.0 with Virtual COM Ports (modems) allows you to send/receive faxes via ISDN line using your standard fax application, that is not desined to operate with CAPI 2.0, for example Microsoft Fax.
ISDN Username (number)
This option enables to include Calling Number (CallerID) in the CAPI 2.0 message when doing outgoing call. By default Fax Voip T.38 Modem uses Default Username specified in the VOIP settings as ISDN number but you can override it in this field. On the other side, this parameter can be overwritten by the Outgoing Call Routing settings. Username consisting of letters is ignored, so digits should be used to include CallerID in the CAPI 2.0 message. Depending on the properties of your ISDN card, CallerID can be ignored and overridden. If you enter an incorrect ISDN number that does not satisfy your ISDN settings, the outgoing call can be rejected. Note that when using username consisting of letters, such error is not possible.
Use Default Username
To modify ISDN Username (number) field, uncheck this option. If this option is checked, Fax Voip T.38 Modem will use the Default Username specified in the VOIP settings as ISDN Username (number).
CAPI 2.0 applications expect and provide voice data coded according G.711 A-law or according to G.711 u-law. Select the G.711 codec that shall be used on your system.
In this area you can view detailed information about ISDN CAPI 2.0 subsystem used on your computer. This indicator works when the Fax Voip T.38 Modem Service (Fax Voip T.38 Modem application) is running and Enable ISDN CAPI option is checked (see more details in the VOIP Settings chapter). The following information can be displayed: