It still the case that the majority of regular broadband connections are associated with a telephone service , so having a landline phone ,( even if it’s only used for testing purposes ) is useful, you could check that you have dialtone , that the correct number is present, obviously no dialtone , or if the wrong number is presented if you make an outgoing call, indicates an issue that could also affect the broadband.
If you are one of those customers that has no telephony on the broadband ( not that you just don’t have a phone connected ) , then obviously these simple checks cannot be done .
If you report a fault and it’s closed by your supplier , usually there is an option to reject the fault being closed and re open the fault report …if there isn’t this option, you will need to re report the fault , (if the fault was never fixed )