A computer system for detecting abnormalities in a call signal, the system comprising: - a first device situated in an originating call network, the first device configured to send call signals to a second device situated in an terminating call network, wherein the second device is coupled to a second registry that stores call signals' data received at the second device as terminating call records; and - a first registry coupled to the first device and configured to, in real-time: obtain, from the first device, call data sent in a given call signal, and store the obtained call data as an originating call record in the first registry; send, to the second registry, a first verification request containing the originating call record, and receive a first verification response, and in response: detect, by processing response data included in the first verification response, a discrepancy between the originating call record and terminating data in the second registry; receive, from the second registry, a second verification request that includes, as request data, a terminating call record stored in the second registry, and in response: detect, by processing the request data: (i) whether an originating call record exists in the first registry that corresponds to the request data, and (ii) a discrepancy between such existing originating call record and the request data, and send, to the second registry, a second verification response based on the processing of the request data, - wherein the first verification request and second verification request include a calling A-number, a called B-number, a call event mark, number portability information, and roaming information. - a first device situated in an originating call network, the first device configured to send call signals to a second device situated in an terminating call network, wherein the second device is coupled to a second registry that stores call signals' data received at the second device as terminating call records; and - a first registry coupled to the first device and configured to, in real-time: obtain, from the first device, call data sent in a given call signal, and store the obtained call data as an originating call record in the first registry; send, to the second registry, a first verification request containing the originating call record, and receive a first verification response, and in response: detect, by processing response data included in the first verification response, a discrepancy between the originating call record and terminating data in the second registry; receive, from the second registry, a second verification request that includes, as request data, a terminating call record stored in the second registry, and in response: detect, by processing the request data: (i) whether an originating call record exists in the first registry that corresponds to the request data, and (ii) a discrepancy between such existing originating call record and the request data, and send, to the second registry, a second verification response based on the processing of the request data, obtain, from the first device, call data sent in a given call signal, and store the obtained call data as an originating call record in the first registry; send, to the second registry, a first verification request containing the originating call record, and receive a first verification response, and in response: detect, by processing response data included in the first verification response, a discrepancy between the originating call record and terminating data in the second registry; receive, from the second registry, a second verification request that includes, as request data, a terminating call record stored in the second registry, and in response: detect, by processing the request data: (i) whether an originating call record exists in the first registry that corresponds to the request data, and (ii) a discrepancy between such existing originating call record and the request data, and send, to the second registry, a second verification response based on the processing of the request data, detect, by processing the request data: (i) whether an originating call record exists in the first registry that corresponds to the request data, and (ii) a discrepancy between such existing originating call record and the request data, and send, to the second registry, a second verification response based on the processing of the request data, - wherein the first verification request and second verification request include a calling A-number, a called B-number, a call event mark, number portability information, and roaming information.