A call interlocking system according to the present invention includes a plurality of in-house control apparatuses each including, data relay means for relaying communication data between a telephone and a call control server and communication data between an information display terminal and an information providing server respectively, and interlocking means for determining whether or not it is possible to interlock a telephone call performed by the telephone with a service that the information display terminal requests to start, and for notifying, when the interlocking means determines that the interlocking is possible, a start request of the service including information for specifying the telephone call to the information providing server, and an information providing server that interlocks the service with the telephone call and provides the interlocked service based on the start request of the service notified from the in-house control apparatus.