Implementations are directed to using an automated assistant to initiate an assisted call on behalf of a given user. The assistant can, during the assisted call, receiving a request, from an additional user on the assisted call, for information that is not known to the assistant. In response, the assistant can render a prompt for the information and, while awaiting responsive input from the given user, continue the assisted call using already resolved value(s) for the assisted call. If responsive input is received within a threshold duration of time, synthesized speech, corresponding to the responsive input, is rendered as part of the assisted call. Implementations are additionally or alternatively directed to using the automated assistant to provide, during an ongoing call between a given user and an additional user, output that is based on a value requested by the additional user during the ongoing call.