Using Windows Fax and Scan with a PCI Express Fax Modem in a Hyper-V environment

I have a windows server 2008 R2 machine that is running Hyper-V.  I just successfully installed a PCIe Fax Modem on the host.  I now want to run Windows Fax and Scan from a virtual machine on this host, but cannot seem to get the vm to access the fax/modem device.   How can I have my VM use the Physical FaxModem installed on the host so I can set up faxing?
thanks For all the help...
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Cliff GaliherCommented:
With Hyper-V, exclusive access devices like fax cards don't get passed through to the VMs. There really is no good way to do this.
aerblichAuthor Commented:
is there a work around that I can use?  Also, is this an issue in server 2012 as well?  what about using a usb-based fax modem?
Cliff GaliherCommented:
This is a limitation in all versions of Hyper-V. So yes, 2012 and 2012 R2 have the same limitation.

Unfortunately fax signaling is so dependent on real-time that the usual workarounds like USB over Ethernet or COM over Ethernet simply fail when it comes to faxing. The few times I've seen it attempted, the solution is abandoned during testing or shortly after implementation because of dropped calls, incomplete faxes, and other related problems.  In short, no, I cannot recommend a workaround of that nature.

There is a solution that has long been an option in physical servers (and is something I've been doing for years), but that virtualization has made much more popular. Unfortunately it won't be using your existing fax equipment though, so be prepared for that.

There is a current standard for transmitting fax signals over Ethernet. It is called T.38 and is perfect for virtualized environments. The solution is basically as follows:

A small physical device connects to the telephone network (different devices offer different connectivity options, everything from POTS to T-1 or larger) and "speaks" standard fax protocols, such as T.30 and V.34.

The device has self-contained software that translates the analog signal to T.38 and sends it on the Ethernet wire to the specified server/servers. It works much like a common cable or DSL modem does. They have proprietary software that converts the cable signal coming in over coax to Ethernet and then sends it on. Same deal, and for small single or dual POTS devices, they are about the same size as well.

On your fax server (the one you configure the gateway to point to), you install a T.38 driver that looks to the OS like a fax machine, but has no physical dependency or component. And since it was written for T.38, is not subject to the limitations that a physical device would be. It *expects* the delays and packetized nature of T.38.  In the case of a virtualized environment, you'd install this on the guest VM that you want handling faxes. NOT the parent/host. The parent OS doesn't need to know about it and won't care. So you don't have the sharing problem you have with a physical device.

Since it appears to the OS as a fax device, any program that can talk to a physical fax device can also talk to the T.38 device. That includes the built in fax server role in Windows, or any 3rd-party fax program that uses standard windows APIs for faxing, such as GFI, RightFax, etc.

It is actually a clean and elegant solution with a very high success rate, and actually easier to manage, migrate, or make changes to on the fly as needed than a physical fax device in a computer would be.

For what it's worth, this is basically how Ethernet-enabled all-in-one SOHO printers work as well. The fax hardware is built into the printer itself, and converts the signal to Ethernet, and the "network fax" driver that is installed in the OS is purely a virtual fax device that handles the Ethernet-to-fax API conversion. And, as long as the driver supports it, can also run in a VM. So some people are using this solution without even thinking about it or realizing that is what happens under the hood.

Hope that helps.

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aerblichAuthor Commented:
Thanks for the comprehensive response.  I cant believe that MS would blunder a hardware sharing feature like this.  Just plain stupid.  So many people in the world still depend upon faxing.  I will definitely look into the device you are referencing.
Hi Cliff. Can you tell me what the name of the hardware vendor is that offers the T.38 solution? Thanks.
Cliff GaliherCommented:
Any of the small business audiocodes gateways should do this. They offer various models with different combinations of FXS and FXO ports to mix and match to your needs.
thank you!
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