A method implemented by one or more processors, the method comprising: receiving audio data capturing a spoken utterance of a human, the spoken utterance being received by a voice bot during a corresponding conversation between the human and the voice bot; processing, using an automatic speech recognition model (130A1, 130A2), the audio data to generate a plurality of ASR speech hypotheses; and in response to predicting the spoken utterance includes a unique personal identifier, the unique personal identifier including a unique sequence of a plurality of alphanumeric characters that is personal to the human: processing, using a plurality of machine learning layers (170A1) of one or more ML models, one or more of the plurality of ASR speech hypotheses to generate one or more candidate unique personal identifiers, each of the one or more candidate unique personal identifiers including plurality of corresponding predicted measures, each corresponding predicted measure associated with one or more corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers; selecting, based on the corresponding predicted measures associated with one or more of the corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers, one or more given alphanumeric characters from among one or more of the corresponding alphanumeric characters; generating, based on the corresponding predicted measure associated with one or more of the given alphanumeric characters, a prompt that includes a clarification request that requests clarification of one or more of the given alphanumeric characters; and causing the prompt to be provided for presentation to the human. receiving audio data capturing a spoken utterance of a human, the spoken utterance being received by a voice bot during a corresponding conversation between the human and the voice bot; processing, using an automatic speech recognition model (130A1, 130A2), the audio data to generate a plurality of ASR speech hypotheses; and in response to predicting the spoken utterance includes a unique personal identifier, the unique personal identifier including a unique sequence of a plurality of alphanumeric characters that is personal to the human: processing, using a plurality of machine learning layers (170A1) of one or more ML models, one or more of the plurality of ASR speech hypotheses to generate one or more candidate unique personal identifiers, each of the one or more candidate unique personal identifiers including plurality of corresponding predicted measures, each corresponding predicted measure associated with one or more corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers; selecting, based on the corresponding predicted measures associated with one or more of the corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers, one or more given alphanumeric characters from among one or more of the corresponding alphanumeric characters; generating, based on the corresponding predicted measure associated with one or more of the given alphanumeric characters, a prompt that includes a clarification request that requests clarification of one or more of the given alphanumeric characters; and causing the prompt to be provided for presentation to the human. processing, using a plurality of machine learning layers (170A1) of one or more ML models, one or more of the plurality of ASR speech hypotheses to generate one or more candidate unique personal identifiers, each of the one or more candidate unique personal identifiers including plurality of corresponding predicted measures, each corresponding predicted measure associated with one or more corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers; selecting, based on the corresponding predicted measures associated with one or more of the corresponding alphanumeric characters for each of the one or more candidate unique personal identifiers, one or more given alphanumeric characters from among one or more of the corresponding alphanumeric characters; generating, based on the corresponding predicted measure associated with one or more of the given alphanumeric characters, a prompt that includes a clarification request that requests clarification of one or more of the given alphanumeric characters; and causing the prompt to be provided for presentation to the human.