We are looking into this as well. I called in and while the Sales folks were a little brusk and aggressive, tech support was pretty good. We got a quote for 30 users that seemed very reasonable. Have not done the integration yet but seems not too bad. I need to run socialminer install and get this going for a couple of different customers as well.
We were looking at Tropo but that has a minimum that is a bit expensive.
Webtext is the only economical solution I have come across. Update this thread if you find something. 
Thanks connacht350 - I reached out to them but we're way too small: 6 agents and they seemed uninterested to sell us their product. That's cool; I will keep looking for a low-end vendor. What I did gather is that they pipe the service as a "web chat" on the UCCX and that's how it is presented to the agents. That's a legit design; I was afraid they somehow pipe it via the e-mail interface
