Gatekeeper transport address determination in an internet telephony system using a domain alias

摘要

An Internet Protocol (IP) telephony system cross-references transport addresses of Gatekeepers using a domain name of the IP telephony system. In one embodiment, the IP telephony system is serviced by at least one Gatekeeper and the transport address for each Gatekeeper is stored on a Domain Name Server (DNS). An A record or other suitable record may be employed within the DNS to index the transport addresses of the Gatekeepers to the IP telephony system domain name. When a calling endpoint desires to initiate a call to a called endpoint, the calling endpoint first queries the DNS for the transport address of a Gatekeeper servicing the IP telephony system. The DNS address retrieves a transport address for the Gatekeeper (or multiple transport addresses for multiple Gatekeepers) and returns the transport address to the calling endpoint. When querying the DNS, the calling endpoint may use an identifier such as subscribername@Gatekeeper.ABC.domain where the user name of the called endpoint is "subscribername" and the domain name of the IP telephony system is ABC.domain. Based upon the structure of the DNS query, therefore, the DNS determines that the query is for a Gatekeeper transport address and operates accordingly. The calling endpoint then sends a Locate Request to the servicing Gatekeeper at the transport address returned by the DNS. If the Gatekeeper receiving the Locate Request services the called endpoint, it returns a transport address for the called endpoint. If not it responds accordingly. When the DNS returns multiple transport addresses, the calling endpoint may access each respective Gatekeeper before retrieving the transport address of the called endpoint. With the transport address retrieved, the calling endpoint then initiates a call to the called endpoint.