Please check that you:
did use the line cable provided together with your VOIP phone. It is absolutely necessary to use the PHILIPS original line cable even if it looks like the ordinary line cable you already had from your previous phone.
did plug the right line adaptor (provided in the box) to the provided line cord. You may have found in your box several line adaptors as this product is being marketed in several countries. Please use the one dedictated to your own country and plug the line cord with its adaptor to your network line socket.