Microsoft

Windows NT Server Terminal Server Edition
Windows 2000 Server family
Citrix

Metaframe
Winframe
SCO

Tarantella
GFI Fax 

Faxmaker for Networks
Faxmaker for Exchange
Symantec 

Winfax Pro 
CTI  SOX Telephony solution
Auslinx Longreach Voicegate VIOP server
Lucent/Ascend Multivoice family
Cisco Access Server 5300 series