If you have one of these devices, good luck in getting it programmed! Sprint is 99% clueless as to how these things work, or even what they are. I'd bet you 5$USD that if you called Sprint support, and said "I'd like to activate this "Sprint PCS In Home Connection Terminal"." they would say something like "...is that like an Air Card?". I called them numerous times, and got that every time. Well, finally I found someone that knew what was I had. Unfortunately, they didn't know how to program it. I was told a couple of times to contact Sprint stores in Indianapolis, IN, Richmond, VA, Charlotte, NC, or Minneapolis, MN. Well, as I found by calling them, no one knew ANYTHING about this device.
In case you don't know anything about the device, it is made by Telular. I used to have a GSM version that was on T-Mobile, however they do not cover my area well, and everyone at work is on Sprint... Well, that aside, my quest turned up gold. Someone (who shall remain nameless - just in case they could get in trouble) sent me the programing sheet! Below, you will find the relevant programming instructions:
SPC/MSL (Sprint): 216926
SID (Sprint): 04190
You'll also need your ESN in Hex and Decimal (located on the bottom of the SX5T), your phone number (MDN), and the MIN from your carrier (if used).
If they give you any guff, just tell them you know how to program the unit, and they will usually go ahead with the setup. I had to call the "Advanced Support Desk" at 866-588-9907, which actually got me right in to a technician. I spoke with three of them, and they ALL were very helpful (although they didn't know how to program the unit, but they tried!). The manual from Sprint comes with the Sprint branded units, but the Telular manual is located here. The Telular manual is much more verbose, and has some additional feature codes listed. You may need to use the configuration mode with the SPC instead of the custom or default "12345678" to access some features (like DTARD, for instance).
One more piece of advice... If you want to get the GPS working, and can't mount the antenna in a good location, put batteries in the unit, or use a long cord, and take it outside. Power it up and leave it out there for 20 minutes. It will store the GPS coords in NVRAM, so after that you can power it off and bring it back inside. I was told this by a Telular engineer, so I assume it to be good information :) Unfortunately, there is no diagnostic function for the GPS receiver (lameee!), at least according to the same engineer.