There are macros that define whether it does a TTS or a sound file. When you include voicemail_en_tts.xml it will be set up to use TTS. If you compare that against say lang_en.xml you will see the macro names are the same but what is defined for each prompt is different.
This enables you to mix and match what you want. You can create entirely new prompts if you wanted just by editing the xml.
Excellent explanation of a very cool feature of FS.
Now I will go on a little rant for a second :) If you have static
data,
prompts and the like, it is best to use static files, lower CPU load, etc. If you have dynamic data, say you are reading someones email to them, or providing some other data that cant easily be pre-generated, then you have to use TTS.
That is my opinion, I know others may disagree, but for cpu reasons its best to not use TTS if you can avoid it.
I agree. Until CPU power is cheaper (and more plentiful) than disk space and RAM then static prompts should be static data sitting in sound files that are ready to be played.
For rapid prototyping/testing of a new system TTS is great, you can
work
out all the prompts, then you know what has to be said, how, when, etc. You can then look at either just generating TTS->soundfile prompts or getting them recorded by live talent.
Yup. -MC P.S. - 0xdecafbad = 11011110110010101111101110101101 :)