A CPU in an IP telephone apparatus automatically controls to transmit, from a network I/F to an ENUM server, a request for deleting a NAPTR record when an absent key is pressed. The CPU regularly transmits, from the network I/F to the ENUM server, an inquiry for a NAPTR record of another IP telephone...http://www.google.com/patents/US7751386?utm_source=gb-gplus-sharePatent US7751386 - IP telephone apparatus, ENUM server, IP telephone system and method for deleting terminal information
