The digitized message was then reconverted to a real voice that you heard through your phone. It's technically feasible, and will be tried in at least one community if some folks in Boulder, Colorado, have their way. However, there are special considerations in addition to the ordinary questions of system design to meet the needs of the particular election situation. Privacy could be an issue, as well, if the voter is in a location where others might be watching or listening or electronically eavesdropping. User-friendliness would need to be designed into the system.
Voters have different capabilities.
There are always special cases when a person with no special training uses an unfamiliar machine. Accounting and accountability are a concern. It must be absolutely certain that the computer is correctly recording each voter's choices and accurately summarizing the votes for each candidate. Hopefully, the system will have been designed to be able to accept the maximum number of calls expected at any one time, so that the chance of getting a busy signal will be very small. When the call is answered, the voice would identify its function of providing the voter with election choices and of recording the voter's selections.