In 1972 my interest in computing started with gathering info on Apple II and similar models. 8-255 connects aan. Fax is easy because the callers fax machine will generate a periodic fax sender tone which can be detected by my software.
Older modems send also a tone which selects data.
This will cause the callers modem to send a periodic Data Tone, which is detected by Receive Manager. BBS will be loaded and the host mode will be activated. VCOS modems do not support this feature. If the callers modem does NOT support Data Tone, please let the caller to append ,,,,D,,, to the end of the phone number. The ,,,,D,,, effectively generates a DTMF tone D after some delay.