Shouldn't do. Most BB ISPs give you a dial up number to use in emergencies such as when the BB connection is down. I've certainly used a modem alongside a BB connection on the same line with no problems or noticeable deterioration.
What is ransomware and how do I protect my PC from WannaCry?
Disney layout supervisor Rob Dressel on the challenges of visualising Moana
Siri vs Google Assistant
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.