cepstral voices good for all software, or which not?

[vmars]

Will Cepstral voices work with most tts programs?
I think NaturalReader says you MUST buy
voices from us..
Is that so for Cepstral ?
Do you have a list of which tts pgms that can use your voices.
Thanks!

Strange that this spell checker doesn't recognize Cepstral as a valid word spelling.