Bad phone service

My mother is 76 years old and utilize her home phone to communicate with family and friends but over the last couple months the service has been horrible.  She has purchased multiple sets of phones over the past 3 months.  The internet service is very horrible as well and it seem to be a related problem.  There have been multiple technicians that have performed troubleshooting steps as well as replaced all the equipment in the house and the problem still exist.  I'm writing this message from her account with her permission.  I have worked in the cable industry multiple times over the last 20 years as an escalation technician in the metro Atlanta area in high profile neighborhoods with celebrities and executives of Fortune 500 companies.  I feel that their is a signal issue outside at either tap or the node not to far from her. house.  I would like to thank you in advance for your assistance but this problem needs to resolved because it's a safe risk.