A system to authenticate packetized audio signals in a voice activated computer network environment, comprising: a natural language processor component executed by a data processing system to receive, via an interface of the data processing system, data packets comprising an input audio signal detected by a sensor of a client device, the client device separate from the data processing system; the natural language processor component to parse the input audio signal to identify a request and a trigger keyword corresponding to the request; a direct action application programming interface of the data processing system to generate, based on the trigger keyword, a first action data structure responsive to the request, the first action data structure comprising one or more parameters packaged together to cause a third party provider device to perform an action; a network security appliance to compare the first action data structure with a first characteristic of the input audio signal to detect an alarm condition; a content selector component executed by the data processing system to receive the trigger keyword identified by the natural language processor component and the indication of the first alarm condition, and select, based on the trigger keyword and the indication, a content item for provision to the client device for authentication of the input audio signal; the network security appliance to: receive data packets transmitted between the client device and a conversational application programming interface that established a communication session with the client device, the data packets comprising a response audio signal detected by a sensor of the client device responsive to provision of the content item to the client device; compare a second characteristic of the response audio signal with the first characteristic of the input audio signal to detect a second alarm condition; and transmit, responsive to detection of the second alarm condition, an instruction to a third party provider device (155,160) to disable the communication session established with the client device. a natural language processor component executed by a data processing system to receive, via an interface of the data processing system, data packets comprising an input audio signal detected by a sensor of a client device, the client device separate from the data processing system; the natural language processor component to parse the input audio signal to identify a request and a trigger keyword corresponding to the request; a direct action application programming interface of the data processing system to generate, based on the trigger keyword, a first action data structure responsive to the request, the first action data structure comprising one or more parameters packaged together to cause a third party provider device to perform an action; a network security appliance to compare the first action data structure with a first characteristic of the input audio signal to detect an alarm condition; a content selector component executed by the data processing system to receive the trigger keyword identified by the natural language processor component and the indication of the first alarm condition, and select, based on the trigger keyword and the indication, a content item for provision to the client device for authentication of the input audio signal; the network security appliance to: receive data packets transmitted between the client device and a conversational application programming interface that established a communication session with the client device, the data packets comprising a response audio signal detected by a sensor of the client device responsive to provision of the content item to the client device; compare a second characteristic of the response audio signal with the first characteristic of the input audio signal to detect a second alarm condition; and transmit, responsive to detection of the second alarm condition, an instruction to a third party provider device (155,160) to disable the communication session established with the client device. receive data packets transmitted between the client device and a conversational application programming interface that established a communication session with the client device, the data packets comprising a response audio signal detected by a sensor of the client device responsive to provision of the content item to the client device; compare a second characteristic of the response audio signal with the first characteristic of the input audio signal to detect a second alarm condition; and transmit, responsive to detection of the second alarm condition, an instruction to a third party provider device (155,160) to disable the communication session established with the client device.