I'd check out Jott.
They used to be free but now I see they charge 3.95/mo for basic speach-to-text or 12.95/mo for unlimited (I didn't spent too much time looking at it).
It's not a software. Jott is used by calling an 800 number and uses a predefined list of contacts via the site to send sms and email. Might be what you are looking for....
Thanks button if this helps
