Flowroute, a SIP service provider, recently enabled SMS on all of their phone numbers (DIDs). This means that if you have a DID from Flowroute, your phone number can now be used to send and receive SMS messages.
This article will show you how you can receive those SMS messages with Perl. (You can skip the background to get to that part quicker.)
I first learned about Flowroute at Astricon 2008 (Phoenix, AZ). At the time, I was working for a Residential VoIP carrier and we were always looking for new service providers.
Flowroute immediately distanced themselves from the other providers by (1) sending engineers instead of sales staff and (2) offering Asterisk prompts from Pat Fleet.