Telephone connection and/or cable connection

Telekom to my knowledge as well. However, I didn't pursue it further because we solved it differently.

I have now looked at the prices (dug anyway for electricity/water): Unitymedia for EUR 408.50 (with conclusion of 2Play) and Telekom for the already mentioned EUR 399 (costs are identical with and without contract). Unitymedia would have cost approx. EUR 800 without contract. In my opinion, well spent money if both connections are made.

Why use a phone when you have cables available? I would have saved myself that... you can always install it later if you really need it.

Telekom as already mentioned 399.00
Kabel Deutschland 599.00 with contract
The contract for TV is, as far as I know, still somewhat discounted.

Wofür Telefon, wenn man Kabel verfügbar hat? Hätte ich mir gespart...kann man ja immer noch legen, wenn man es unbedingt braucht.

Well - on the one hand you are more flexible.
If cable causes problems for some reason (every now and then you do read about persistent disruptions), you can switch.
If Vodafone (who bought Kabel Deutschland) decides to push prices up outrageously, you can still look for an alternative (Telekom, 1&1, or whoever).

On the other hand - if you ever want to sell your house, you can offer the potential buyer both alternatives (possibly increasing the value).

Still lay it if you need it:
If it's already been dug up, you might as well use it. Retrofitting later will cost quite a bit more.
However - and this speaks in favor of laying later: Then you would have a modern line installed.

Why use a phone when you have cable available? I would have saved it... you can still install it later if you really need it.

Do you have any idea what it costs to tear up a finished front yard/driveway/asphalted road for a lousy telecom connection? The 399 € is just "peanuts" compared to that. If necessary, I can kick out Unitymedia (or simply do without internet or phone) and fall back on a phone provider. As f-pNo wrote - it's also an investment that increases the value of the house. If I spend half a million on the house (or however much) and go for every little detail, then the 399 € really doesn’t hurt ;)

Well, I would have installed a conduit, then hardly anything would need to be torn open.

And increase in value? You probably don't believe that yourself that anyone would pay for that later in any form ;)..

Besides, I hope that fiber optic connection will be available in 20 years, then you can just lay it again anyway.