This modem needs two stop bits (when sending), so you have to add
CSTOPB to tio.c_cflag = … in tio.c
/ tio_mode_sane().
Also, use #define FAX_SEND_BAUD B19200 and, for fax reception,
#define DEFAULT_PORTSPEED B19200.
Further, the modem is a little bit timing critical - please insert
delay(500) calls at the end of fax_open_device()
(sendfax.c, line 122) and before sending the page punctuation
(fax_command("+FET=...") in sendfax.c, main(), around
line 540).
Also, for at least one Exar 9624 (built into a Compaq notebook), it’s been
necessary to add two delays (\\d\\d) before the AT+FCLASS=0
initialization string in mgetty.c.