Setting up faxing (AudioCodes MP1288, MediaPack MP504/508)

You can set up fax support for an AudioCodes MP1288 and MediaPack MP504/508 (formally M500Li) gateway connected to a fax machine.


This article covers:


Note: This document does not cover setup and provisioning of the MP1288 or MediaPack MP504/508 (formally M500Li). For initial setup, see the quick start guide for the AudioCodes MP1288 gateway. This guide assumes analog ports are already configured and calls to and from the ports are working. Fax parameters will then be assigned to an Analog port that is currently configured.

Limitations of fax over Voice over Internet Protocol (VoIP)

Faxing has known limitations when implemented as a fax over VoIP service. These limitations are technology-based and industry-wide. Zoom and several VoIP companies use the G.711 standard for sending faxes over the Internet. Although that standard is considered reliable, it is still open to interpretation by various providers and cannot be maintained on an end-to-end basis.

Zoom offers a fax over VoIP service that connects a traditional fax machine to the Internet via an analog terminal adapter (ATA). For occasional faxing, many of our business customers find these best-effort fax services to be cost-effective and more than adequate to serve their needs. We encourage you to assess your faxing needs to select the best option for your business.

Zoom cares about providing you with quality services that meet your business needs. If your business is heavily dependent on regularly faxing large, multi-page documents, then we recommend that you maintain an analog line and a traditional fax machine for reliable and consistent performance.

How to set up faxing

  1. Sign in to MP1288 or MediaPack MP504/508 (formally M500Li) web interface.
  2. Click the SIGNALING & MEDIA tab.
  3. In the left-side navigation panel, click MEDIA then Fax/Modem/CID Settings.
  4. Change the following fields to Events Only:
    • Fax Transport Mode
    • V.21 Modem Transport Type
    • V.22 Modem Transport Type
    • V.23 Modem Transport Type
    • V.32 Modem Transport Type
    • V.34 Modem Transport Type
  5. Change the following fields as specified below:
    • Fax Relay Max Rate (bps): 9600bps
    • Fax/Modem Bypass Coder Type: G711Ulaw or G711Alaw, depending on region
  6. Click Apply.
  7. In the left-side navigation panel, click CODERS & PROFILES then Coder Groups.
  8. Verify the Coder Group Name at the top is set to AudioCodersGroup_0 has the below coders listed.
    Coder NamePacketization TimeRatePayload TypeSilence Suppression


  9. Create a new Coder Group named AudioCodersGroup_1 with the below codes.
    Note: Make sure only G711U-law/G711A-law is in this group. This will force the use of G711 codec for faxing.
    Coder NamePacketization TimeRatePayload TypeSilence Suppression
    • Click +New to create a new coder group.
    • In the index field, enter 1.
    • In the name field, enter AudioCodersGroup_1, then click Apply.
    • Under the Coders Groups listing, highlight the newly created AudiCodersGroup_1, find the Coders Table 0 items below, then click to open it.
    • Under the Coder Name column, select G711U-law/G711A-law depending on your regions.
      Note: Make sure only G711U-law/G711A-law is in the group. This will force the use of G711 codec for faxing.
  10. Click Apply, then click the left arrow to return to the Coders Groups page.
  11. Navigate to CODERS & PROFILES, then Tel Profiles, then click +New to create a new Tel Profiles, and specify these fields:
      • Name: Enter a name to identify the profile; for example Fax Profile. Index: 1.
      • Profile Preference: 1
      • Fax Signaling Method: No Fax
      • Enable Digit Delivery: Disable
      • Dial Plan Index: -1
      • Call Priority: Disable
      • Coders Group: Select AudioCodersGroup_1 created in step 8
      • RTP IP DiffServ: 46
      • Signaling DiffServ: 24
      • Enable Early Media: Disable
      • Echo Canceler: Line Echo Canceller
      • EC NLP Mode: Adaptive NLP
  12. Click Apply.
  13. In the navigation panel, click GATEWAY > Trunks & Groups > Trunk Groups.
  14. In the Tel Profile Name column, assign the Tel Profile created in step 11 to each port that a fax machine will be connected to.
  15. Click Apply.
  16. On the top right of the page, click Save.

How to use a template to apply fax settings to the device

You can use a provision template as an alternative to applying fax settings to your AudioCodes MP1288 or MediaPack MP504/508 (formally M500Li) device which is less prone to errors than directly applying those settings to the device.

  1. Create a provision template or append it to an existing template.
  2. Copy the content from the text file, then in the Template box paste the content.
    • The blank lines between sections in the content provided are required for the parameters to work, so make sure the content is copied as is.
    • You can modify the name "AudioCoderGroups_1" (name of the coder group) of "Fax" (name of the Tel-Profile) in the template as desired.
    • Modify the TrunkGroup line to match where your fax port is located and your corresponding Zoom Phone 20 digits registration ID.
    • To find out the corresponding Zoom Phone 20 digits registration ID, log in to the MP1288 web interface. On the upper right corner, locate Actions>Configuration File, and click Download INI File.
    • Open the downloaded INI file, and locate the TrunkGroup line corresponding to the step below.  Copy the 20 digits Registration ID value and replace the original 35738224149678037377 value with the sample TrunkGroup line below.

    • In our template example, where the fax line is located on port#3:
      TrunkGroup 2 = 0, 255, 3, 3, "35738224149678037377", "Fax", 255, 1;

    • Make adjustment to the above line according to your port# where the fax line is. For example, if your fax is on FXS port 1, the above line should be:

      TrunkGroup 0 = 2, 255, 1, 1, "your 20 digits Zoom Phone registration ID", "Fax", 255, 1;

  3. Assign the template to your AudioCodes MP1288 or MediaPack MP504/508 (formally M500Li) device.
    • If the device is online, it will auto-provisioned with the fax setting parameters from the provision template.
    • If the device is offline, follow the assisted provisioning process from the web portal device page to fully provision the device.