A data output apparatus checks data accumulated state in the accumulating unit at a preset check interval, and changes at least one setting among an initial accumulation amount to be used as a basis for starting to output the data accumulated in the accumulating unit, an upper accumulation limit amount to be used as a basis for discarding accumulated data, and a check interval, according to a discarded state of the data based on check results. Therefore, in the data output apparatus such as an IP telephony terminal apparatus, it is possible to prevent sound interruption and limit a lowering of communication quality.