Fax in Exchange 2007 Unified Messaging

Unified Messaging provides the functionality of having voice mail, email and fax to a single location that is the user’s mailbox. In Exchange 2007 Unified Messaging the fax feature is limited to inbound fax only. Which means that, an external or internal caller can call to the UM server and leave a fax message for a user with Exchange 2007 mailbox. A user can receive fax in their mailbox the following manner:

  1. A user can have a specific extension for fax. Their mailbox will have a corresponding secondary UM extension (eum type proxy address) which is dedicated to fax.
  2. Users have a single number for both Voice mail and Fax. The caller can send faxes to the voice mail extension. Should users pick up the phone, they can either transfer the call to their own extension, or hang up to let the fax machine resend.
  3. Users can have a shared mailbox dedicated to fax messages. The fax message in this case has to be manually forwarded to its destination or via custom application.

Protocol for Fax

UM supports T.38 protocol for fax media. The signaling information is sent by the VOIP endpoints (gateway or IP-PBX) as SIP over TCP. UM relies on the VOIP endpoints to detect the fax tone and take appropriate action in handling the media.

Configuring the Fax Feature in UM

The default configuration on Unified Messaging is already set for receiving fax. Which means the dial plan, the user and the UM server are all by default, Fax enabled.

A UM enabled user account has a parameter called ‘FaxEnabled‘ which determines whether the user is enabled for fax or not. If this attribute is ‘not set’ then the user defaults to the settings of the dial plan.

The command for enabling fax for a dial plan:

Set-UMDialPlan –identity MyDialPlan –FaxEnabled $true

When you enable a dial plan for Fax all the users within that dial plan are enabled for fax unless user level attribute for fax is set to ‘false’.

The duration of the fax call is impacted by the parameter ‘MaxCallDuration‘ parameter of the dial plan. It is set to 30 minutes by default.

You can also configure fax on the UM mailbox level. You have to set the UM mailbox attribute ‘FaxEnabled‘ to ‘true’ to enable the user to receive fax. After the user is fax enabled you can add a new proxy address of ‘eum’ type as an alternate number for fax or you can use the same number for voicemail and fax messages.

The command for enabling fax for a user:

Set-UMMailbox –identity UMUser1 –FaxEnabled $true

If the dial plan is configured for fax but a user’s ‘faxEnabled’ attribute set to ‘false’, the user will not receive fax messages.

Configure Fax Attributes for a UM Server

This section explains how to use the Exchange Management Console and the Exchange Management Shell to configure the number of concurrent fax connections that are accepted by a Microsoft Exchange Server 2007 Unified Messaging (UM) server. The range of concurrent fax calls is 0 to 200, and the default value is 100.

You need to have exchange organization administrator permission to perform this operation.

Using Exchange Management Console

Following is the step by step procedure:

  1. In the console root of the Exchange Management Console, expand the Server Configuration node, and then click the Unified Messaging node.
  2. In the result pane, click to select the UM server you want to configure.
  3. In the action pane, click Properties.
  4. On the UM Server Configuration tab, under the Maximum concurrent fax calls section, in the data field, type the maximum number of concurrent fax calls.
  5. Click OK.
Using Exchange Management Shell

Following is the command:

Set-UMServer -Identity UMServerName -MaxFaxCallsAllowed 100

Configure Fax attribute for UM Mailbox Policy

You can configure couple of settings in the UM Mailbox Policy to customize the fax that the user’s receive.

Adding Fax ID

You can add fax identifier for all incoming Fax by editing the UM Mailbox Policy. The parameter is ‘faxId’. By default the value is set to ‘Microsoft Exchange’

Following is the command:

Set-UMMailboxPolicy –identity MyUMPolicy –FaxId “Fax Service”

Adding a default message

You can add a default message for all incoming Fax by editing the UM Mailbox Policy. This message is added within the body of the email message that has the fax message. The parameter is ‘faxMessageText’

Following is the command:

Set-UMMailboxPolicy –identity MyUMPolicy –FaxMessageText “This Fax is received by UM Server.”

Fax Call Flow to UM server

The fax call flow to UM server is very similar to the voice mail call flow. For details go to:


Fax Message in the client

Fax message will arrive as email message with fax message as an (tif) attachment. After receiving the fax message from the gateway, UM server will treat the message the same way as with voice mail message. The message will look like the following screen shots in the client machine, Outlook or OWA client:

Seema Rahman

Comments (19)
  1. jirka says:

    Is it necessary condition to receive fax having installed extra HW in UN server(e.g. fax card). Thank you.

  2. Seema Rahman says:

    In order to receive fax you don’t need any extra hardware on your UM server. Our supported gateways and IP-PBXes have the capability to recognize fax message and send it to the UM server. However, UM only supported inbound fax. For outbound fax you will need fax related hardware to send out fax.”

  3. mdgrkb says:


    I would like to know if there is any software product that will allow setting up a lab for Unified Messaging.  I mean besides an Exchange 2007 server, something (not hardware) to work as a pbx or the sort.

    I came accross this product, but haven’t tried it yet.


    Anyone has tried it?  Anyone knows a product that will allow a UM demo without using an actual PBX?

    Thank you very much

  4. jeremyk says:

    Two options, but one is hardware, but I think it is reasonable:


    This allows you to demo 100% of the UM features with a telephony experience.

    ExchangeUMTestPhone.exe (located in the bin folder) will allow you to demo the AA and VM features well.

  5. questionable says:

    so… does UM/receive fax/voicemail work if you have a regular pci modem with a regular phone line into it?

  6. RJ says:

    I have tried to use the UM Test Phone, but the server never answers.  Do you have to be connected to a PBX of some kind in order for the test phone to work?

  7. Seema Rahman says:

    You dont have to be connected to the PBX. One thing to make sure is –

    – if you are running the test phone from a client make sure you have a UM IP gateway object with the IP address of the client machine.

    – If you are running the test phone from the UM server iteself then make sure you have a UM IP gateway object with the IP address of the server.

    Following are the instructions for using the test phone –


  8. Seema Rahman says:

    the incoming call to UM server needs to be in VOIP network using SIP protocol for signaling. A regular PCI card do not have that capability. You will need a VOIP gateway that can talk to the telephone system and translate the data to a format (SIP and RTP for voice and T.38 for Fax) that UM can understand.

  9. RJ says:

    I followed the directions in the link before and the test phone appears to connect, but always goes to idle.  I am not able to connect to the automated attendant.  I do have the UM IP gateway object set as required.  Is there something else that I could be missing?

  10. RJ says:

    One thing I did notice is that some of the files required for the UM Test phone do not exist in the specified directories or have slightly different names than specified in the document.

  11. Seema Rahman says:


    i saw that the location of the files have changed. You will need the same files though. So make sure you have the exact files that are specified in the direction. Couple of other things i would recommend, test with the default hunt group that has no specific pilot number. And turn up diagnostics logging and check app log to see if you get any errors –

    Get-EventLogLevel | where {$_.identity -match ‘Unified’} | set-eventloglevel -level Expert

  12. RJ says:

    Ok, I can now call the server and get the default test voice mail message.  However, I cannot leave messages or dial extensions through the Test Phone.

  13. seema rahman says:

    the user must be UM enabled. With UM test phone you need to check the ‘diversion’ checkbox and put the user’s extension, and then make the call. (leave the ‘pilot identifier’ and ‘caller-id’ field blank.)


  14. TWfromWI says:

    If an incoming fax fails, the UM user still receives an email that a fax was received.  Is it possible to prevent emails for failed faxes?

  15. Seema Rahman says:

    there can two types of emails sent to user when fax fails – if an INVITE is sent but the data transmission fails (as if caller hung up during the call) a missed call notification will be sent, and you can turn that off for the user. the catch is that all missed call notifications are turned off.


    If the fax message is incomplete still the user gets an email with incomplete fax as attachment. This cannot be turned off.

  16. Jamey Stubblefield says:

    Is Exchange 2007 a viable replacement for RightFax?

    How would you address outbound faxing without signing up with a 3rd party Internet fax service provider?

    A 3rd party solution for outbound faxing is not an option for confidential documents.

  17. Sabas says:

    Does Exchange 2007 Fax have OCR, bar code reading capability?  Can it be used for application processing?  Most FAX servers provide this.

  18. Seema Rahman says:

    Currently we do not have OCR capability built-in within Exchange 2007.

  19. Seema Rahman says:

    Outbound faxing feature relies heavily on client-side technology for different printer drivers. Windows faxing solution can provide that feature for now.

Comments are closed.