SMS only works with the major carries. For example, my phone is through a company called I Wireless (http://www.iwirelesshome.com). There are on the sprint pcs network, but that option doesn't work for my phone. It needs to go through <phone number>@iwirelesshometext.com
I was able to find the mon-lib.pl that contains the carrier definitions and manually add mine; but a control panel or option to specify a new carrier would be a great help.