I m currently using an Aeotec Gen 5 doorbell/siren, for custom voice messages. It is an Z-wave device that works locally. However, it does not use TTS. You have to produce the message files either by recording the message in your own voice, or using a program like Zabaware Reader to convert Text to speech and then save the file.
Since the Aeotec Gen 5 is no longer available commercially and the Gen 6 device no longer supports customer message files, it is not a viable an option as it once was. There is another member on the forum who has a Gen 5 for sale.
I just ordered an Ecolink ISZW7-ECO chime + siren that allows you to store custom audio file on an SD card, Like the Aeotec Gen 5, you have to create the custom files yourself, although some default sounds are included. That would allow you to keep your alerts local.
