How to Stop Scam Calls on Landline

Hi! I need some advice on how to help an aunt who has dementia and who is receiving spam call after call on her home phone. I spoke to a rep who said if she changed from copper line home phone to fiber that this would filter out 98% of spam calls. We scheduled a service tech to come out and he said this was not true that all he was doing was installing internet. We even thought about changing her number but the rep said they would still find her. What advice can you give to help. She had a cell phone but "lost" it so this is not an option and we have thought about some of the elder phones like RAZ etc. Can you help? Thank you!