Patent ID: 8346850

Claim:
A method of operating a Domain Name System server, the method comprising the steps of: receiving a query containing as a search key, a Domain Name System name of a destination terminal for which a Session Initiation Protocol (SIP) address is not assigned; determining whether an Internet Protocol (IP) address for the Domain Name System name is registered with the Domain Name System server; upon determining that an IP address is registered, returning the registered IP address to a sender of the query; and upon determining that an IP address is not registered: determining that the destination terminal is offline; in response to receiving the query and determining that the destination terminal is offline, triggering a wake-up message to be sent to the offline destination terminal via an out-of-band signaling link different than a communication link subsequently utilized to carry data, wherein the wake-up message is sent without any prior application level protocol exchange with the offline destination terminal, and the wake-up message causes the destination terminal to go online and establish a data session; retrieving an IP address allocated to the destination terminal as a result of establishing the data session, wherein the Domain Name System server retrieves the IP address from a Dynamic Host Control Protocol Server; and returning the received IP address to the sender of the query; wherein the method saves network resources by allowing the destination terminal to remain offline until the triggered wake-up message causes the offline destination terminal to go online and establish the data session.