internet goes down

[brennkaz]

when making a landline call there is a crackling interference and the internet goes down

[TimmyBGood]

@brennkaz 

If you are using FTTC, do you have a filtered master socket or a plug-in microfilter for every telephone handset?

[brennkaz]

yes a microfilter in the main phone box

[TimmyBGood]

@brennkaz 

I'd suggest replacing that if you can.

Perhaps also try a different telephone handset with the same filter.