1. A method comprising: at a fraud detection system: responsive to sub-account usage data of at least one sub-account of a telecommunication platform, controlling the fraud detection system to calculate at least a first fraud score of a first sub-account from the sub-account usage data, the sub-account usage data including at least sub-account configuration data and communication history data, the first sub-account being managed by a first parent account in the telecommunication platform; responsive to a determination by the fraud detection system that at least the first fraud score of the first sub-account satisfies a fraud threshold, controlling the fraud detection system to provide an external service provider system of the first parent account with a notification of illicit behavior of the first sub-account, the fraud detection system providing the notification via the telecommunication platform, wherein the first sub-account is a telecommunication platform account of an external system that uses a service of the external service provider system and a service of the telecommunication platform.