Moin Moin @Tz1993 ,

if the cable from the basement to your flat is broken, than the owner of the cable is your landlord.

He can hire an electrician to replace the line.

Where is the cable broken?
In the house - local electrician. Landlord must place order!
Outside the house - DSL provider
 

I heard that statement last year from a Vodafone supporter.

But last month I got a different statement from an O2 supporter:

I will relocate in about 2 months. The new flat in an appartment building gets new electricity and other cabling. So I asked O2 who will be responsible for the DSL-cable into my flat. I got the answer that O2 will provide the cable directly into my flat. So in that case no landlord involved within the house. (Assuming that the answer from the O2 supporter was correct ...)

@Tz1993: So I would suggest you ask your DSL-Provider about this. Then they will tell you whom to contact - if necessary.

However, this still means that the service provision (interface) takes place in the apartment, but nothing about the responsibility of who is responsible for cable installation and repair. 

No, not in that case.

I am also owner of that house - so I am also my own landlord. So I explicitly asked if I have to do anything as the old cables are old and shitty. I was explicitly told that O2 will send a technician that will take care of that in case there are problems.

And for my understanding then O2 is also responsible for any repair, if necessary - they provide the line, so they are responsible …

(But I am mentally prepared that I got a wrong information from the O2 supporter ...)

Well, sure, if you pay for it too!
The technicians who repair lines are employees of the network operator. O2 does not own the DSL network and needs service providers for this. Of course, small repairs like replacing a telephone socket(TAE) are done as troubleshooting. However, this does not apply to line relocations and lengthy troubleshooting. 

I know that O2 is something like a “reseller” there. But extra costs were not mentioned there. All included in the setup fee.

From that it looks as if that line is property of O2 or their “provider”. So they should also be responsible for repairs. Otherwise they would have to get in touch with the landlord to negotiate the line into the flat. What if there are other solutions in the house an a separate DSL-Line is not feasible? (Theoretically spoken)

This will never happen!
Believe it or not.

What would be the juridical construct in that case? You can not install something (the line in the house to the flat) making the owner of the house responsible for it, without getting the permission from him to do so.

Even the line itself would have to be allowed by the owner if there wasn’t one before - at least by my understanding of law.

Hi @Tz1993 

Any update regarding your broken DSL Cable? 

Is your DSL back online or is it still broken? 

We would love to hear from you. 

Best Regards Matze 

Hi, the technician came just now. He told me he didn’t know which part was broken and he will call me back if he get the answer. It makes me really disappointed. I do not know when I can connect to Internet again but I have to pay the fee of Internet. And it is really inconvenient for home office without Internet.

Hi @Tz1993 

Your trouble ticket tells me a new technician appointment was made for next thursday (april 15th), between 8 am and 2pm? 

Can you confirm that? 

Best Regards Matze