So a scenario I run into often, but I'm not sure if this type of service would work very well for me. Before I go into specific cases, I initially wondered why an SMS interface? An app for the phone that works offline/online would be something I would more expect.
I tend to meet new people in bulk. For example, I go to meet a new client and get introduced to 5 people. Or I go to a networking event and am bouncing around meeting some new people. In either of these scenarios, your solution wouldn't work well for me.
In the first scenario, it would be a pain for me to send 5 different texts and walk through the prompts. So an interface for mass input would be great. In the second scenario, I'm not looking to break away from my conversations to type in information into my phone. This is a much tougher problem because really I want to remember who I just met without having to distract myself from my next conversation.
Good luck with SW!