Patent ID: 8259921

Claim:
A method of processing a number portability call, the method comprising: transmitting a call request message to a donor network server based on dialed number information of a called terminal; receiving a response message according to number portability of the called terminal from the donor network server, in correspondence to the call request message; detecting routing number information of the called terminal based on the dialed number information, according to reception of the response message; and performing call setup to a recipient network server associated with the called terminal based on at least one of the dialed number information and the routing number information, wherein: the call request message is an initial address message and the response message is a call release message, and the detecting of the routing number information comprises: maintaining a number portability database including routing number information; and detecting, from the number portability database, the routing number information of the called terminal corresponding to the dialed number information, when the called terminal is determined as a terminal using a number portability based on the call release message, wherein: the donor network server or the recipient network server is a server that is connected by No. 7 protocol, the initial address message or the call release message is a message that is based on No. 7 protocol, the call release message is a message in which the donor network server sets at least one of a cause value and a diagnostic value of the call release message according to a number portability of the called terminal, and the determination using the call release message determines whether the called terminal is the terminal using the number portability based on at least one of the cause value and the diagnostic value of the call release message.