SMS message or phone alert with no internet access

I would like to make a temperature sensor for a semi truck/trailer. The sensor would ride in the trailer and monitor temperatures. If the temp fell out of threshold, ideally the driver would receive a text message. The challenge is doing this without a cellular network. Is there a way to create a wifi network (without internet, just a private network) and send SMS messages over it?
I'm open to any suggestions outside of this as well, bluetooth or any other methods that may make sense.
thanks in advance.

bairdmar:
I would like to make a temperature sensor for a semi truck/trailer. The sensor would ride in the trailer and monitor temperatures. If the temp fell out of threshold, ideally the driver would receive a text message. The challenge is doing this without a cellular network. Is there a way to create a wifi network (without internet, just a private network) and send SMS messages over it?
I'm open to any suggestions outside of this as well, bluetooth or any other methods that may make sense.
thanks in advance.

Write an app on your phone, that logs into the Arduino on a local network in the truck.

SMS go thru the phone systems, either directly from a phone or thru an internet server with a cell interface.

If you spent the bucks you could illegally setup a femto cell that hijacked nearby phones. Wouldn't be cheap or easy.
chuck.

Bluetooth might work. Is this transmitter in the front of the trailer or the back? The range to the back might be too far for low-power Bluetooth.

Otherwise there's lots of radios available that will work for Arduinos. Look at JeeNodes or Moteinos for Arduino-compatible processors that have the wireless built in. You can use those same wireless modules on any Arduino, or maybe Xbee or a dozen other methods.

Wifi would be my last choice. That uses lots of power and is usually only useful when your other end must be Wifi and your data rates are very high, like for video.

An Arduino Yun has WiFi built in and can easily be set up as a server. Anything that can connect over WiFi could connect to it. No external wireless infrastructure is required.

I think you can use a cheap ESP8266 WiFi module in the same way - connected to an Uno or other Arduino.

The Yun has the advantage of a Linux computer that you can program with Python.

The only concern I have is that the metal of the truck and trailer may interfere with wireless signals so you would probably need to experiment with the location of the transmitting and receiving devices.

...R

Thanks for the responses.

MorganS, you make a good point about power consumption for WiFi, that is a concern since everything is going to have to be on battery.

If I were to use radios as you mentioned, can i use that to communicate with a phone via some kind of adaptor, or would I need a receiver in the cab that was displaying temps?

Ideally there would be 2 monitors. One toward the front, and another toward the back of the trailer.

A less expensive and more reliable solution would be some wire and an LED.

If you want to communicate with a phone the practical choice is either Bluetooth or WiFi. Bluetooth has a short range.

...R