Has anyone used Tropo in a serious capacity? I'm currently using Twilio for SMS, but Tropo's integration with various IM services and very slightly cheaper SMS pricing may be compelling enough for me to switch.
I'm Tropo's product manager. We've got quite a few companies using Tropo in significant capacity. In fact, because of our ability to scale and telephony expertise (Tropo's a product from Voxeo, the largest worldwide voice application host), we regularly see customers switch from other providers to Tropo.