3. Symptom
Sending to or receiving from certain people always seems to fail. Why?

Resolution
If you are experiencing difficulties with sending / receiving check if this is happening with all devices sent to or receiving from.

If you can successfully send to other devices it is most likely that there is an incompatibility between your fax modem and the other fax device.

Try the following:

Check on the Equisys web site (http://www.equisys.com/) that you have the latest version of the Zetafax FCLASS driver
If using Zetafax 6 or later, use the Zetafax configuration program to change the modem settings to enable Class 1 operation - this helps with many compatibility issue
Check with the modem manufacturer that you have the latest version of the modem firmware.
Configuring modem transmission speeds:

Run the Zetafax configuration program.
Under devices, right click on your modem device and select Edit.
Select More.
Set maximum baud rate speeds to 9600. Save the settings.
Restart the Zetafax Server.
Alternatively, you can configure device settings in SETUP.INI

Edit the following file using NOTEPAD: zfax\SYSTEM\Z-DB\SETUP.INI
Locate the section which refers to your modem device, e.g. [FCLASS-1].
Add the following lines:
BaudRate: 9600
TransmitSpeed: 9600
ReceiveSpeed: 9600

If after applying the above changes and you are still encountering problems, add the following lines to SETUP.INI

VoiceCommands: OFF (please note DTMF tones will not work with this line)
ReceiveReversed: Yes
CleanFaxes: YES