Nuisance call detection device and method

A nuisance call detection system comprising:

• a telephone;
• and
• a server configured to be communicably connected to a plurality of the telephones, wherein
• the telephone includes;
• a memory configured to store a voice signal during a telephone call;
• and
• a processor configured to analyze the voice signal for one telephone call to calculate a plurality of pieces of determination information used for determination as to whether the telephone call is a nuisance call, the plurality of pieces of determination information including a stress evaluation value for a speaker, who performs a telephone call using the second telephone, and including a number of keywords, the stress evaluation value being calculated based on the voice signal for the one telephone call, the keywords being previously specified and being detected from the voice signal for the one telephone call, the number of the keywords being acquired by accumulating a result of the detection of the keyword, calculate information on a length of a conversation for the one telephone call, calculate each weighting factor for a respective one of the plurality of pieces of determination information in accordance with the length of the conversation, calculate a nuisance call evaluation value based on a value by summing up values each calculated by multiplying each weighing factor by a corresponding one of the plurality of pieces of determination information, and determine that the one telephone call is a nuisance call when the nuisance call evaluation value is greater than a predetermined threshold, output nuisance call information indicating that the one telephone call is a nuisance call when it is determined that the one telephone call is a nuisance call, and wherein
• the server includes:
• a memory configured to store information about the nuisance call detected in the plurality of the telephones;
• and
• a processor configured to transmit to the plurality of the telephones a telephone number in which the decided incoming call is rejected after a telephone number is decided in which an incoming call is rejected as a nuisance call based on information about the acquired nuisance call.

A nuisance call detection method for determining whether a telephone call is a nuisance call, in which, in response to a request from a first telephone, a connection is established between the first telephone and a second telephone, and detecting the nuisance call, comprising:

• analyzing, by a processor, a voice signal for one telephone call to calculate a plurality of pieces of determination information used for determination as to whether the telephone call is a nuisance call, the plurality of pieces of determination information including a stress evaluation value for a speaker, who performs a telephone call using the second telephone, and including a number of keywords, the stress evaluation value being calculated based on the voice signal for the one telephone call, the keywords being previously specified and being detected from the voice signal for the one telephone call, the number of the keywords being acquired by accumulating a result of the detection of the keyword;
• calculating, by the processor, information on a length of a conversation for the one telephone call;
• calculating, by the processor, each weighting factor for a respective one of the plurality of pieces of determination information in accordance with the length of the conversation;
• calculating, by the processor, a nuisance call evaluation value by summing up values each calculated by multiplying each weighing factor by a corresponding one of the plurality of pieces of determination information;
• determining, by the processor, that the one telephone call is a nuisance call when the nuisance call evaluation value is greater than a predetermined threshold;
• and
• outputting nuisance call information indicating that the one telephone call is a nuisance call when it is determined that the one telephone call is a nuisance call.

A non-transitory computer-readable recording medium having stored therein a program for causing a computer to execute a process for determining whether a telephone call is a nuisance call, in which, in response to a request from a first telephone, a connection is established between the first telephone and a second telephone, and detecting the nuisance call, the process comprising:

• analyzing a voice signal for one telephone call to calculate a plurality of pieces of determination information used for determination as to whether the telephone call is a nuisance call, the plurality of pieces of determination information including a stress evaluation value for a speaker, who performs a telephone call using the second telephone, and including a number of keywords, the stress evaluation value being calculated based on the voice signal for the one telephone call, the keywords being previously specified and being detected from the voice signal for the one telephone call, the number of the keywords being acquired by accumulating a result of the detection of the keyword;
• calculating information on a length of a conversation for the one telephone call;
• calculating each weighting factor for a respective one of the plurality of pieces of determination information in accordance with the length of the conversation;
• calculating a nuisance call evaluation value by summing up values each calculated by multiplying each of the plurality of pieces of determination information by the weighting factor;
• determining that the one telephone call is a nuisance call when the nuisance call evaluation value is greater than a predetermined threshold;
• and
• outputting nuisance call information indicating that the one telephone call is a nuisance call when it is determined that the one telephone call is a nuisance call.