In RelayFax 6.6 and newer, voice modems and CAPI 2.0 boards can now be used to detect DTMF when answering calls. This feature can be enabled from the options tab of modem properties. The DTMF digits received after answering the call are treated as DID when routing. When using the Black Ice engine, you must specify the number of digits to listen for. With the Alt-N engine and CAPI boards, the number of digits field is not used and the line is monitored for 10 seconds or until a fax tone is received. The timeout duration is set by the VoiceAnswerTimeout parameter in the [FaxServer] section of RelayFax.ini.
To send DTMF, use the '@' character to separate the phone number from the DTMF digits. For example, FAXNUMBER: 1234567@1234 will dial 1234567 and wait for silence (lack of ringback), transmit the DTMF digits, and start fax transmission. The modem-specific parameters of the '@' character should be documented in the modem manual under the D command. For CAPI devices, there are several DTMF options in the [CAPI] section of RelayFax.ini to control the delay before and after sending DTMF digits, the length of each digit and the gap between digits in milliseconds.
Additional Comments
For RelayFax 6.7, the digit separator was changed from '@' to 'x'.