Using VoIP Services on a Locked Modem

Some Internet Service Providers (ISPs) “lock” the VoIP features of their supplied modems. This means you can’t directly change the VoIP settings inside the modem’s interface.

Good news: You can still enjoy VoIP calls by connecting your VoIP-capable equipment alongside the modem.

There are two main ways to do this:

1. Analog Telephone Adapter (ATA) – lets you use a standard analog phone.

2. VoIP-Enabled Telephone – connects directly to your network and stores VoIP settings.

This guide will show you step-by-step how to set up both methods.

Option 1: Using an Analog Telephone Adapter (ATA)

What You’ll Need

1. A modem with a working internet connection

2. An ATA device 

3. An analog phone (standard landline-style or a VOIP-compatible handset)

4. An Ethernet cable (RJ45) and phone cable (RJ11)

5. Your VoIP account details (username, password, SIP server address)

Step 1: Power Off Your Equipment

Turn off your modem, ATA, and phone to avoid connection issues during setup.

Step 2: Connect the ATA to Your Modem

• Plug one end of the Ethernet cable into the ATA’s WAN or Internet port.
• Plug the other end into an available LAN port on your modem/router.

Step 3: Connect Your Phone to the ATA

Attach the phone cable from your analog phone to the ATA’s Phone or Line port.

Step 4: Power On Devices

• First, turn on your modem and wait until the connection is established.
• Then power on the ATA.
• Finally, plug in and power your phone (if applicable).

Step 5: Configure the ATA

• On a connected computer, access the ATA’s configuration page (refer to your ATA manual for the correct IP address or login method).
• Enter your VoIP SIP settings: server address, username, and password. For details, see this article.
• Save your changes.

Step 6: Test the Line

• Pick up your phone and check for a dial tone.
• Try placing a test call to confirm audio quality.

Option 2: Using a VoIP-Enabled Analog Phone

Some analog-style phones come with built-in VoIP functionality, letting you skip the ATA entirely.

What You’ll Need

• A modem with a working internet connection

• A VOIP-compatible telephone

• An Ethernet cable (RJ45) 

• Your VoIP account details (username, password, SIP server info)

Step 1: Connect the phone to your modem/router via Ethernet.

Step 2:  On a connected computer, access the phone’s configuration page (refer to the manufacturer's manual for the correct IP address or login method).

Step 3: Enter your VoIP SIP settings: server address, username, and password. For details, see this article.

Step 4: Save your changes.

Step 5: Test for dial tone and call quality.

Troubleshooting Tips

• No Dial Tone: Double-check all cable connections and verify ATA power.

• Registration Failed: Ensure your SIP credentials are entered correctly. 

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