i'm moving this discussion to the mailing list -- keeps me from
answering the same question multiple times
what you are describing is xforms relevancy. you can show a variety of
prompts based on answers to previous prompts. you can see example
forms at http://code.google.com/p/opendatakit/source/browse?repo=forms
or read the form design guidelines at
currently, you can't send an sms as an event, but that's functionality
that you could add to your version of collect.