Patent ID: 7756111

Claim:
An IP telephone access system which includes an IP telephone terminal, a customer's terminating device connected to the IP telephone terminal, and an intra-office terminating device connected to the customer's terminating device, comprising: an address management table, in the customer's terminating device, for coordinating a logical link identifier of each customer's terminating device and an IP address of the IP telephone terminal; an ID management table, in the intra-office terminating device, for registering the logical link identifier of each customer's terminating device connected to the intra-office terminating device; a server, in an IP network in which information between the IP telephone terminal and the server is transferred by IP packets, accessible from the intra-office terminating device; and a subscriber's number management table, in the server, for coordinating the identifier of the intra-office terminating device, the logical link identifier of the customer's terminating device, the IP address of the IP telephone terminal and the subscriber's number; wherein a source IP address in a call request packet transmitted from the IP telephone terminal is collated in the customer's terminating device to determine whether or not the source IP address is a match with any one of IP addresses stored in the address management table, and only the call request packet transmitted from the IP telephone terminal whose IP address is stored in the address management table is accepted.