Connecting your ATA to your Fax Machine

Setting up your ATA for Fax over VoIP

This guide walks you through configuring an Analog Telephone Adapter (ATA) to work with a fax machine over a VoIP connection. Faxing over VoIP can be sensitive to connection quality and settings, so it's important to follow each step closely.

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Finding the ATA IP address

Look up the IP address in your router based on the MAC address.
Enter the IP address in your browser.
Log in with the username: admin and the password: admin.

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Setting up VoIP account

Go to Quick setup.
For User ID enter the Account ID of your VoIP account.

Go to Freedom.
Click on Admin
Click on VoIP account.
Behind the VoIP account, you'll see the account ID. Hover over it to easily copy it.

For Password enter the password of your VoIP account.

Go to Freedom.
Click on Admin
Click on VoIP account.
Behind the VoIP account, you'll see the password. Hover over it to easily copy it.

Enter ha.voys.nl for Proxy.
Click on Submit.
Go to Voice and click on Line 1.
Go to Supplementary Service Subscription.

SIP supplementary services are services that can extend your telephone service. These services can include features like call forwarding, redialing, and conference calls.

Go to Audio Configuration and copy the settings below:

Preferred codecs: 1. G711a 2. G711u
Echo canc enable: No
Fax passthru codec: G711a
Fax passthru method ReINVITE
Fax enable T38: yes

Click on Submit.

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Other optimal settings for the fax

RTP packet size: 0.010
Insert VIA rport: yes
FXS port impedance: 600+2.16uF
NAT mapping enable: yes
NAT keep alive enable: yes
Use DNS SRV: yes
User ID: <account id of the VoIP account>
Password: <the password>
Preferred codec: G711a
Use pref codec only: yes
Silence supp enable: no
Echo canc enable: no
Echo supp enable: no
Fax passtru codec: G711a
Fax enable T38: yes
The ATA will now restart.

The ATA is now configured and ready to use! Connect the fax plug to Line 1 of the ATA.

FAQ

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Why isn't my fax working over VoIP?

One common issue is that the transmission speed (baud rate) of the fax machine is set too high for stable operation over a VoIP connection.

If possible, try lowering the baud rate in your fax machine’s settings. A slower speed can improve reliability and increase the chances of successful transmission over VoIP.

Voys does not provide support for physical fax machines over VoIP. Instead, we recommend using our Fax inbound service, which offers a more reliable and modern alternative.

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What is T.38 protocol support and does Voys support it?

The T.38 protocol is used to send faxes over SIP connections. Voys supports T.38 by default on both VoIP trunks and VoIP accounts, allowing you to send and receive faxes reliably over our VoIP platform.

VoIP Hardware

Fax inbound

Fax Outbound