Unable to call out via the Internet with TP-Link Telephony modem router

Phenomenon

The telephony has been registered successfully via TP-Link modem router, but you may get trouble to make outgoing calls when one or more phones connect to the TP-Link VoIP modem router. It is also possible that only certain phone numbers cannot be called. The problem occurs sporadically or always. This article will guide you to do troubleshooting if you meet this situation.

Troubleshooting

Note:

Take the actions described here once at a time. After each action, check to see if the problem is resolved.

Make sure telephony is registered properly

Log into the web interface of the modem router, click Advanced-Telephony, and check if the telephony is registered with green check symbol.

How to log into the web-based interface of the AC VDSL/ADSL Modem Router

If not, check this FAQ.

Upgrade the firmware of the modem router

Refer to the FAQ to update your modem router to the latest firmware.

Turn off SIP ALG

In the user interface of the modem router, click Advanced > NAT Forwarding > Uncheck "Enable SIP ALG" > click on Save.

Deleting Call Blocks

In the user interface of the modem router, click Advanced >Telephony > DND & Call Blocking, delete all entries and click on Save.

Maintain an Internet connection at all times

Calls to your Internet number reach the Telephony modem only when connected to the Internet. Make sure that the modem always connects to the internet.

Set up the Telephony on another modem router

To eliminate the problem, you can set up the same telephony settings on another modem router to do a comparison test.

If another modem router encounters the same problem, contact your provider to check the phone number and credentials and ask if your provider has any suggestions on this issue. Also check the settings on your phone.

If the above steps can’t fix the problem, please contact TP-Link technical support team and provide us the following information.

Model number, hardware version and firmware version of your TP-Link device;

How to find the hardware and firmware version of my TP-Link device

Your internet and telephony service provider;
The model number of your phone;
The result of each above troubleshooting steps.