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VPN IP Phone - One Way Audio on TPG NBN

Level 1a



Issue: One way audio on VPN IP Phone.



The VPN IP Phone is connected successfully on the internet as it was able to connect to the VPN.

A call is successfully connected internally and externally.


However, the issue of one way audio is when a call is coming from an external number or calling an external number (e.g. mobile number). The receiver of the VPN IP Phone cannot hear anything but the other end receiver able to hear the voice coming from the VPN IP Phone.


Port Forwarding has been tried. DMZ has been tried. But, the issue is still the same.


The confusing part here is that, I have a colleague that is also with TPG NBN and now have the same modem that I have, is NOT encountering the issue.


Is it possible to verify or check from TPG side if any ports is getting blocked from my service address? or to check if there's any configuration that needs to be done from TPG's end to resolve this issue?


Additional notes:

- This is not the normal phone at home. This is a VPN IP Phone.

- Contacted the manufacturer of the modem (TP-Link) but didn't resolve the issue.

- Contacted the internal network and cisco engineers in the office but still have the issue. They said that the modem is working (tested the VPN Phone as well) with Telstra and iiNet when they tested it.

- TPG replaced my modem as well as part of the restart issue but still have the one way audio issue.


Thank you.





Hi @captlhou,


Welcome to TPG Community!


TPG don't block any ports on the network or on an specific service address.


As the service and modem has been tested and confirmed working, you might need to check further with your VPN provider if there's anything that they are missing when checking your service.


Customers are free to purchase or have their own VPN provider, however, support for non TPG service is limited as it is not possible for us to have an updated knowledge of their system.


Should you require further assistance, please let us know.


Have a great day.


Level 4

Hi @captlhou


"The confusing part here is that, 
I have a colleague that is also with TPG NBN 
and now have the same modem that I have, 
is NOT encountering the issue."

If this is true.

Have you tried to check the VPN IP Phone handset it self?


Level 1a

Hi @2fly,


Thank you for your reply.


Yes, I did check the VPN IP Phone Handset. I even tried using the speaker of the phone but still having the issue.

It is not the phone as the exact phone that I am using is the one that I have tested in my colleagues house.




Level 1a

Hi @BasilDV,


Thank you for your reply.


VPN connection is not an issue. The phone can connect to the VPN successfully.

It can even make a call but the issue is happening only when the call is connecting to an external number.


I will give your feedback to our support team to give them some updates.