FIXED: Unimodem Modem Audio sound driver missing in Windows 10
UPDATE: Version 1607 (Builds 14393.479 and later include this fix to Modem.sys for both x86 and x64)
If you updated from an earlier version of Microsoft Windows including Microsoft Windows 7, Microsoft Windows 8.x or Microsoft Windows 10 version 1507 (build 10240) to Microsoft Windows 10 version 1511 (builds 10586) or later, the Unimodem Audio driver for your ‘dialup’ fax/voice modem may no longer be installed in Windows.
This can prevent some features of your voice mail/fax software from operating properly. Audio progress from your modem may be missing and if your fax modem has voice capability, it may not be available with the voice software you are using.
Members participating in this thread have provided steps to reproduce the problem and one member has verified the source of the problem to be the modem.sys file provided with Microsoft Windows 10.
UPDATE: A representative from Microsoft has confirmed this issue with the Modem.sys file and a solution has been applied in version 1607 Build 14393.479 of Windows 10. Verify your version of Windows 10 by right-clicking Windows Start, Click Run, and type ‘WinVer’ (Or Windows Key+R and type WinVer and press Enter) also, you can verify the properties of the Modem.sys file in your Windows\System32\Drivers folder. The properties should report version 10.14383.479 or later.
Microsoft Answers Threads:
We tested the voice and fax functionality with FaxTalk FaxCenter Pro 9, FaxTalk Messenger Pro 9 and FaxTalk Multiline Server 9. All voice mail functionality is working normally without the presence of the Unimodem Audio Driver in Windows 10 version 1511 or later. Call screening and playback for incoming calls in voice mode is working.