Configure Fax Passthrough C

To enable passthrough, follow these steps:

1. Make sure "Enable Fax/Modem Relay" is enabled.
2. Make sure "Detection Mode" is Standard.
3. Make sure "Relay Mode" is Passthrough.
4. Make sure "Enable switching to FAX relay upon CNG tone" is checked.
5. Make sure "Detection type" is "Silence Suppression off"
6. Make sure the Codec is the same as the remote end.