For PSTN phone lines use the phone socket. To check if a telephone or filter is defective try making a call with only one phone connected at a time. Broken Phone Line Concept Of Communication Problem Sponsored Line Phone Broken Problem Communication A Broken Phone Phone Communication Problems Learn about accessibility at TELUS. Problem with phone line . Switch off all your phone equipment INCLUDING at the power points. Plug a working phone not cordless into the main phone socket this is usually where the phone line enters your premises. See if you can make calls from it. If the light flashes with only one telephone that is the defective telephone or filter. Ad Search For Relevant Info Results. Other culprits include the following. Ad Find China Manufacturers Of Voip Phones. A guide if youre having problems with your landline phone. Disconnect the base unit from the telephone line and connect the line to a known working telephone for example your neighbours phone. ...