Device for gnokii for use on AT&T in the US

[Jeffrey T Eaton]

I'm looking to set up a monitoring system which can send alerts via  
SMS with gnokii, and I'm looking for recommendations for a device which:

- is known to work well on the AT&T network in the US
- is supported well with gnokii
- isn't a phone, but is just a simple serial/usb device, or even an  
ethernet-type device that can be accessed via HTTP or other simple  
protocol.

I only care about the ability to send and recieve SMS messages over  
the air, and have my monitoring system easily interface with it.  I  
don't want or need to be able to make voice calls, or establish  
internet connections over the air.

Any suggestions?

-jeaton