I'll be moving into a new build in a week and have ordered bt ultrafast 100. However the installation date is 3rd of Jan and that's a bit long to wait. I know the house already has the white box (don't know official name) and been told its ready for service. Does this mean I can use my own router? Is there any need for an engineer to come install more stuff?
Thanks in advance
Until you move in, and see whether there are any alarm conditions on the optical box, its difficult to say.
If you have a wireless router with a WAN port on it, then there is a chance it may work, but the service may not actually be activated yet.
For a new build to have a working internet connection someone must have an account. Unless someone lived there before you there will be no service. Unless it was a showhouse with working internet.
As long as the ONT is installed and registered there is no need for an engineer.