From COSMOTE App you can check your landline connections.
COSMOTE App
1st step
Login to COSMOTE App and go to the bottom of your screen. Select from “Quick find” the “Check Connection”. If you have more than one landline, please select the one you want.
Alternatively
Select the “Management” category. In the “Support” menu, select “Check Connection”.
2nd step
Select “Check connection”. Once the check is complete you will see the result on the screen.