VoIP Phones - Zyxel VMG/DX Routers

Back up to the VoIP Configuring page
From AAISP Support Site


Specifically tested on a DX5301-B2, EX5401-B1, EX5601-B0 and a VMG8825-B50B.

The instructions will work for any Zyxel router on the same firmware platform ("Opal").

NOTE: There is a bug in some firmware versions of the EX5601 router. The phone will not ring for a long time while the person calling receives ringing tone. If you pick up the phone while the phone is "ringing but not ringing" the call gets answered.
For each inbound call the delay will increase until the router is power cycled.
Workaround: Set the region to USA or NOR (the ring style you hear will change for inbound and outbound calls! The ring people calling you will hear does not change).
Fix: Firmware "V5.70(ACDZ.2)C0_20231201" and newer do not suffer from this problem.


Zyxel VMG8825-B50B Router Ports.jpg

Plug the analogue telephone into the green PHONE1 port on the back of the router.


If your router is on the default IP visit: and log in.

First go to the Menu --> VoIP --> Phone option.

Zyxel VMG8825-B50B Phone Menu.png

Make sure the region is set to GBR - UK and the service mode as Europe.

Zyxel VMG8825-B50B VoIP Regional Settings.png

Go to the Menu --> VoIP --> SIP option.

Then the SIP Service Provider tab.

Click on the edit symbol next to the "ChangeMe" entries and fill in the details below. Note that you are required to fill in a "SIP Proxy Server Address" but this is not the same as "Outbound proxy server" which can be found hidden under the drop down advanced section. AAISP DO NOT NEED OUTBOUND PROXY SET!

Zyxel VMG8825-B50B VoIP Service Provider settings.png

Click the little arrow to show further settings and change the "DTMF Mode" to "RFC 2833".

Go to the SIP Account tab.

Click on the edit symbol next to the first "ChangeMe" entry.

Enter the details as shown on your AAISP Control panel for the telephone number you want to setup. Remember to generate and set a password on the AAISP control panel for the number if one isn't already set.

Zyxel VMG8825-B50B SIP Account Settings.png

After about 10 seconds AAISP should show the device as registered on the account and the Menu --> System Monitor --> VoIP screen should show it as registered on the router.

Zyxel VMG8825-B50B VoIP Status.png