ENUM server and congestion control method

A congestion control method performed in an ENUM server for receiving an ENUM query from another network that includes a sender terminal and transmitting, to the other network, connection destination information that corresponds to a call destination number of a receiver terminal that is indicated in the ENUM query and managed in a local network, the congestion control method causing the ENUM server to execute:

• collecting traffic information regarding calls that include call destination numbers from call processing apparatuses in the local network, calculating a call amount per unit time for each call destination number, and storing the call amounts per unit time as calculated call amount information in a storage means;
• receiving an ENUM query from the other network;
• extracting a call destination number included in the received ENUM query, referencing the calculated call amount information, and determining that calls to the extracted call destination number are in a congested state if the call amount regarding the extracted call destination number exceeds a predetermined threshold value;
• if it was determined that the call destination number included in the received ENUM query is in the congested state, determining whether or not the ENUM query is to be a limit target based on predetermined limit processing;
• and
• if it was determined that the ENUM query is the limit target, generating an ENUM answer that indicates connection unavailability, setting a Time To Live (TTL) value of the ENUM answer to 0, and transmitting the ENUM answer to the other network.

A non-transitory computer readable medium storing a congestion control program for enabling a computer serving as an ENUM server for receiving an ENUM query from another network that includes a sender terminal and transmitting, to the other network, connection destination information that corresponds to a call destination number of a receiver terminal that is indicated in the ENUM query and managed in a local network, the congestion control program causing the computer to execute:

• collecting traffic information regarding calls that include call destination numbers from call processing apparatuses in the local network, calculating a call amount per unit time for each call destination number, and storing the call amounts per unit time as calculated call amount information in a storage means;
• receiving an ENUM query from the other network;
• extracting a call destination number included in the received ENUM query, referencing the calculated call amount information, and determining that calls to the extracted call destination number are in a congested state if the call amount regarding the extracted call destination number exceeds a predetermined threshold value;
• if it was determined that the call destination number included in the received ENUM query is in the congested state, determining whether or not the ENUM query is to be a limit target based on predetermined limit processing;
• and
• if it was determined that the ENUM query is the limit target, generating an ENUM answer that indicates connection unavailability, setting a Time To Live (TTL) value of the ENUM answer to 0, and transmitting the ENUM answer to the other network.