Availability and pricing of things like Twilio is pretty variable outside of the US. Last I checked Twilio wasn't going to work for most SMS down here in NZ for example. Not sure about voice.
Exactly right. We're based out of Australia so it's horribly annoying to see so many cool startups that don't provide service to us down here. The majority of voice/sms startups these days use either Twilio or Tropo (including us) so that severely limits the cost or even use of a service for Australians.