Im a recent custober since beginning of this Feb to sunrise adsl. They initially sent me the wrong modem as it wasn't wireless and now they said they will send as i specified the 'Zyxel Prestige 660HW' wireless router/modem'. So I think you'll have no problems with using your existing modem. Cant comment on voip as I haven't looked into this yet. Deal I have includes free swiss fixed line calls for 12 months.