These days this entails the more or less the following:
Techie calls and confirms appointment to come and do site survey (i.e. locating the tower from your house, best place to locate the external installation). Once confirmed, he will drill a few holes in your freshly painted wall, chimney etc, mount a (small) TV type bracket, and install a short pole (+- 1m). Outdoor CPE attaches to top of pole. Runs outdoor (black) Ethernet cable (through roof and ceiling) to a place in your house, where you want the indoor router located, with a plugpoint. You need to provide 2 x two pin plugs. One to power the indoor router, and 1 to power the POE to the outdoor CPE, which is actually also a router. This is my setup, at least. Mine took 3 hours to complete, but included some haggling with the call centre and techie using a malfunctioning CPE to look for signal.
All stuff is switched on, and tested, after which you sign some sort of acceptance form.
If he can't find signal, he leaves. (When you order the service, they will check that you are in coverage) They will not even send out a techie if not, but as mentioned many time before, theoretical map coverage does not mean you get good enough signal. Hence the actual site visit.
Good luck!