This modem came in a compaq machine and has been referred as Compaq Netelligent 56K ISA Fax Modem, which has a rockwell chip (RCVDL56ACF/SP) on it.
These are the original drivers for Win95 and Win 98, so should solve your problem.
The following files are found inside the driver download file.
|Locate.exe||84.3 KB||2 Nov 1998|
|DISK.ID||43 bytes||2 Nov 1998|
|CPQ_400.inf||31.8 KB||2 Nov 1998|
|README.TXT||12.4 KB||15 Apr 1999|
|Install.exe||106.1 KB||2 Nov 1998|
|SETMODEM.EXE||172.6 KB||2 Nov 1998|
|Setmodem.msg||22.6 KB||2 Nov 1998|
|Escd.rf||270 bytes||2 Nov 1998|
|Install.dat||12.8 KB||2 Nov 1998|
|Kbhit.com||2.7 KB||2 Nov 1998|
|vssver.scc||240 bytes||2 Nov 1998|
|Comcheck.exe||84.4 KB||2 Nov 1998|
|Dwcfgmg.sys||64.9 KB||2 Nov 1998|