Fax Server
Zero Admin
With the new Dashboard
Bulletproof Security
With SSL certs and NGINX
Install on $150 Appliance
Intel MiniPC architecture
New, Intuitive Windows Client
More themes, more UC
More CRM Integrations
Scripting Interface to add your own
Improved Integrated Web Conferencing
iOS and Android apps included
Personal Click2Meet URLs

Fax Server

Configuring Fax Server

On this topic

Configuring Fax Server


Fax Receiving Configuration

Configuring Fax Machines / Fax Servers

Step 1: Creating a Fax Extension

Step 2: Connecting a Fax Machine using an ATA

See Also


3CX Phone System includes a fax server that allows you to receive faxes. 3CX Fax Server is based on the T.38 standard protocol and requires a compatible supported T.38 VoIP gateway or provider. VoIP providers and gateways must be configured according to our configuration guides, so that fax reception is enabled. It is also possible to use a VoIP provider that does not support the T.38 protocol, however, the quality of the fax implementation between VoIP providers varies and therefore can not be guaranteed.

Fax Receiving Configuration

To receive faxes, you must configure a line or a DID to be dedicated for receiving of faxes, so that all calls on this number are forwarded to the 3CX Fax Server. The 3CX Fax Server will then receive the fax, convert it to PDF and email the fax to the configured email address. To configure fax reception:

  1. In the 3CX Management Console, select the Inbound rule for the port or DID which will be dedicated for receiving faxes.
  2. From the “Office hours” routing options, select “Send fax to email of extension”.
  3. Select the extension that should receive incoming faxes. If you select Default Email Address, incoming faxes will be sent to the email address configured for the virtual fax extension number. You can configure the email address of the default virtual fax extension from the “Fax Machines” and select  “888” then click “Edit Fax Extension”.
  4. Alternatively you can forward incoming faxes to the email address configured for a user’s extension. This even allows you to create multiple DID rules and give personal fax numbers.

Configuring Fax Machines / Fax Servers

The “Fax machines node in the management console lists all known “Fax extensions” including the extension used by the 3CX Fax Server. These “Fax extensions” are similar to a normal extension and require an authentication ID and password to login to the SIP server.

3CX Phone System included a pre-configured fax extension (ext: 888). This extension is used by the 3CX Fax Server for incoming fax calls, which will then be routed to an email address. In addition, 3CX Phone System can be configured to proxy fax calls (T.38 traffic) to a fax machine connected to an ATA or another software based T.38 fax server, by creating additional fax extension.

Step 1: Creating a Fax Extension

To create a new fax extension:

  1. In the 3CX Management Console, select “Fax machines” > “Add Fax Extension”.
  2. In the “Fax Server Extension Number” field, specify the fax extension number. Any calls forwarded to this extension will be assumed to be a fax and receive a fax tone.
  3. Specify the Fax Server Authentication ID and Password – These credentials will be used by the ATA / 3rd party fax server to login to 3CX Phone System.
  4. If this extension is used by the 3CX Fax Server, you can specify the default email address to which all faxes should be sent to.
  5. If this extension is used for an ATA or 3rd party T.38 fax software, the extension will be used only to register to the SIP server and receive T.38 fax traffic.
  6. If the fax extension is created to be used for an ATA or 3rd party T.38 fax software, you can configure the “Outbound Caller ID” to be sent when an Outgoing Fax call is made.

Note: You must restart the fax service for these changes to take effect.

Step 2: Connecting a Fax Machine using an ATA to the Fax Extension

Once you have configured the fax extension you can connect the fax machine to a supported ATA device and configure the ATA device to connect to the fax extension. The guide Configure Your Fax Machine with 3CX Phone System outlines this process step by step.

See Also

You might also be interested in:

Ask a Question

Please only post questions in regards to the document you are currently reading.
Technical support or pre sales questions must be posted via the support or sales channels and such comments will be deleted. Thank you for understanding

Leave a Reply

  1. David

    For 3CX Fax server, inbound topic, some of our customers send large faxes that tie up the fax analog phone line. Is there such thing as fax queue or simultaneously inbound faxes?

    September 11, 2015 at 12:51 am Reply
    • Charalambos Eleftheriou

      @David, thanks for the question, there is no fax queue, if the number is busy no other faxes can be received. You can though increase the amount of fax lines you have.

      September 11, 2015 at 10:16 am
  2. Is there any way to configure the 3CX Fax Server to send the created PDF documents to a folder on a shared drive or to a printer instead of to an email?

    September 24, 2015 at 3:48 pm Reply
    • Charalambos Eleftheriou

      @Ray, thanks for the question. Fax via email is the only way that 3CX can send faxes.

      September 24, 2015 at 4:59 pm
  3. Chris Gapske

    I am attempting to setup faxing but it appears there is a 40 page limit.

    It does a good job until I need to get over 40 pages ? Can you tell me where to change that setting ?

    November 2, 2015 at 10:36 pm Reply
    • Charalambos Eleftheriou

      @Chris, thanks for the question. There is no limit set on incoming faxes. But would it not be more cost effective to scan, digitally sign and send via email. In any case, if you are having issues with receiving faxes for this many pages, check that your provider isn’t limiting you from receiving the fax. If your using a gateway with an ISDN or Analogue line you may also want to check that you do not have line quality issues.

      November 3, 2015 at 4:38 pm
  4. Johnny

    For 3CX Fax Server, what are the codecs I should use in my VOIP Provider under Advanced Tab? I have properly configured the 3CX Server with the Inbound DID dedicated to the Fax Server; however, when I send a test fax to the DID and I received errors on my end. The codecs i’m using for my default VOIP Provides are G.711 U-law, G.711 A-law, and G729. Perhaps these codecs are not support by the 3CX Server?

    March 18, 2016 at 12:27 am Reply
    • Charalambos Eleftheriou

      @Johnny, check with your provider that they support T.38 fax protocol. This must be enabled on their side for fax to work. Audio codecs have no bearing where fax is concerned.

      March 18, 2016 at 10:28 am
  5. Jamie

    I’m just configuring a PBX for a new customer but I am confronted with a problem.
    Our customer has 2 fax numbers, 1 for sales and 1 for support. Each number needs to go to a different e-mail address. Faxes for sales need to go to sales@customer.com and faxes for support need to go to support@customer.com.
    How do I configure this? It looks like I can only add just 1 fax extension with an e-mail address?
    We are running 3CX v14 SP 2 Professional.

    April 8, 2016 at 7:25 pm Reply
    • Charalambos Eleftheriou

      @Jamie, Fax server extensions only allow one with an email but you can direct fax numbers to extensions with email addresses configured and have as many as you like.

      April 8, 2016 at 8:42 pm
  6. Jamie

    Ok so it needs just 1 fax server and that way it can send multiple faxes to e-mail addresses? That is great! Thank you for the quick reply!

    April 8, 2016 at 8:53 pm Reply
  7. Stuart Hash

    what Codecs will 3cx support for faxes to email/pdf? t.38 only? or g.711 or g.729. is there going to be any changes to which codecs are supported our SIP provider does not support fax over t.38 (faxes within the SIP trunk work fine I.E. intra-office faxing but not inter office faxing from outside lines that may originate on t.38. therefore we must forward all fax numbers coming inbound to an external number with a fax server on the other end. once the call has been routed to a “Non-SIP” line, the faxes work fine.

    June 28, 2016 at 12:40 am Reply
    • YOu have 2 options : T38 or G711 pass through. Those are the 2 standards.
      Our fax server supports T38 and it will not change.
      You can connect an ATA and that will provide you T38 pass through.
      If you have this problem it means that your provider is weak in this area. You need to contact them and inform them that faxes can be received from other numbers not only from provider to provider numbers. Its like you can call only from vodafone to vodafone.. What is this?

      June 28, 2016 at 6:38 am
  8. Sylvain

    Does 3cx fax server support G711 passthrough?

    July 13, 2016 at 9:54 pm Reply
    • @Sylvain Fax server supports T38 only. For G711 Passthrough you need to connect an ATA or your SIP Trunk can support G711 Passthrough.

      July 14, 2016 at 9:43 am
  9. G

    Is there any way to add an IVR option to send fax? Like “Dial 8 to send fax”

    August 11, 2016 at 10:18 pm Reply
  10. G

    @Nicky, Is there any workaround to give a caller the option to send fax once he reaches the Digital Receptionist? We have a customer who does not have an extra line (and can’t add a new one) to dedicate to Fax attention.

    August 15, 2016 at 6:38 pm Reply