I have no experience of the brand, but have used Novatel PCMCIA modems before, this model contains everything you need; text based SMS, RS232 interface, looks like a TCP stack onboard, as well as an output port and two I/O ports. It also looks to be a recent, possibly current model.
If the phone is only going to receive texts could you reverse engineer it using the display, you'd have to get the phone to bring up the incomming message using its keypad and transistors, but once done you'd be able to pick up the text data that the phone sends to the display.