Firewall issues.

Firewalls in routers (if you are using a physical telephone or adapter) and in your PC (if you are using a softphone) can cause problems for VoIP because it's their job to prevent un-asked for external data entering your network - they do their best to stop it.

Many modern routers are becoming clever at detecting the sort of traffic VoIP sends and allows it in but some others don't.

Some have a process running called SIP ALG which is supposed to help your router handle VoIP traffic but generally it just gets into a tangle with it. If it's switched on in your router, please turn it off.

Please also check that your phone(s) are registering to (NOT

If you're still having problems, we have a a service called the NAT Proxy which sorts pot problems of one way calls.

If you experience one way audio or you are able to make outbound calls but not receive inbound, just add:

as your Outbound Proxy.

Adding the NAT Proxy in a telephone or adapter

To do this you will need to enter the IP address of your phone into the web browser of a PC that your telephone shares a network with and find the Outbound Proxy field. If you don't know how to do this please consult the manual for your telephone or adapter, otherwise email support at and we will try to help.

Adding the NAT Proxy in the X-Lite Softphone
To do this in our X-Lite softphone press F8 when the phone is open and you will see the menu. Add into the outbound proxy field shown there. There is more information here:

Please Note: Please try your phone without the outbound proxy first; most equipment will not need it and adding it unnecessarily may cause problems. If you have the proxy added and experience problems please remove it & often it does the opposite of what you would expect!

Voipfone Customer Services

iNet Telecoms Ltd (Voipfone)
Sovereign House
227 Marsh Wall
E14 9SD
United Kingdom

Registered number: 05168033
Vat Registration Number 858850966

Telephone: 020 7043 5555
Fax: 020 7043 5556


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