I can't see anything. Our land line phone is a BT4600 and it has worked perfectly on VM and still is after the changeover. Its just the problem of the emergency phone ringing at the same time as the land line on an incoming call. To be honest I'm beginning to wonder how useful this extra phone is considering it will only ring 999 and not the numbers my wife and I need to access with our health issues in an emergency. If there is no easy fix I'll try and get the phone returned. We both have mobiles we could use.
Amazing that VM can issue a product for which there is no manual available, anywhere.
In the general VM phone guide on pages 38 / 39
it shows the icons available (one of which is 'Phone ringer’s switched of' so it must be possible to do it).
On the same pages the image of the phone shows the word 'Menu' on the bottom LHS of the display screen.
If you press the button with the little white dot beneath 'Menu', does that brings up any options for you? You may need to use the right dot key to select options.
You will probably need to use the up/down arrows in the middle to move up/down the menu tree and look for 'phone settings' or something similar if available. Motorola phones might call it 'silent mode'
Pages 40/41 show you some other options you can set via this 'menu' route.
What is available in the menu might depend on how locked down VM has made the emergency phone setup.