Again, that is not recommended but it will usually work. Solid state ringers have gone a long way toward reducing noise on the LAN when ringing. If they are getting a lot of calls they need to be tolerant of LAN hits. That is not usually a problem in a residence. In a business with a dozen people banging away on the LAN and a phone ringing all the time it may show up as a problem. I would be sure I warned them of all of these issues and keep WiFi or running the right cable as their "plan B"
