www.tropo.com and www.teleku.com does both international voice and SMS I believe. There's also www.cloudvox.com, but I'm unsure if they also support international.
If you buy a number from us outside the US, we can't do SMS on that yet, but we're working on it. In the meantime, feel free to send texts to and from anywhere from your US number. We won't even charge you any extra for the international sending.
Teleku is now owned by Tropo and as such can do international SMS as well. CloudVox doesn't do SMS worldwide, but I was talking to one of their founders recently and he mentioned they're working on it.