Designing something to send message via radio, preferrably to cell phone

Okay, I am new here, so please bear with me - I am trying to help a friend of mine out who operates an animal rescue here. They sometimes use live traps to catch animals - but in the winter time here, there is always a danger of an animal getting caught in the trap and freezing. How hard would it be to build a device that, when attached to the trap, would send a signal to a cell phone when the trap was activated? It would save the rescuers from making hourly trips all night to a trap.

Thanks in advance

Andrew

Depending on how much budget they had vs how techie they wanted to be, either:

Xenta/Sumvision etc Wifi infrared webcam: £40
Android mobile phone: £40
Low-use PAYG mobile data plan: £7.50/month
Car battery: £35
Car battery charger: £10
Upturned plastic box to protect it all with hole cut out for camera to see through so you don't get bounceback from the IR LED's: Free!

Set the Android to tethering mode. Set the camera to send an email with attached image when movement is detected (images are small - around 45k so this won't eat all your data). Then you even get to see what is trapped! No PC needed as camera does all this and has its own webserver.

OR if £125 seems a bit extreme just to save a night-time walk...

Buy a cheap pair of two way radios (£10-£15). The standard PMR 446 type should have a line-of-sight range in the open of about 2km.
Set the transmitter to send "end of transmission" sound (most have this feature).
Take case off transmitter, hotwire the PTT button to a 555 timer chip (£1 including the 2 resistors and once capacitor you'll need) generating a 5 second pulse every 5 seconds, and wire a 6v battery so that when the trap closes, the circuit is made. Then you get 5 seconds of audio (to hear if anything is squealing!), then a tone burst which should awaken any sleeping rangers listening at the receiving end! Cost: £16, no ongoing charges.

For such a low volume application, trying to use an existing device would seem to make sense. A device like the SPOT may be a good match due to its ability to operate in extreme temperatures with long battery life. You would need to figure out a way to tie into one of its buttons to activate the message to be sent. Another nice thing about this device is you get GPS coordinates with the message. Being satellite based you don't need to worry about cellular coverage in remote areas. Keeping the antenna area clear of snow/ice may be problematic as it would with any transmitter.

http://www.findmespot.com/en/index.php

Hi Andrew if you want to do this then see the following

If you want strictly mobile phone use then you want sms modems or consider zigbee as an alternative then construct an embedded solution around a micro of your choice to activate on triggering of trap sending message to mobile phone or number of phones

Details as follows
http://www.warburtech.com/products/gsm/?gclid=CPmYiMXKi7UCFXHLtAod838ArQ

Or see this site
http://www.circuitsathome.com/mcu/programming/interfacing-arduino-to-a-cellular-phone

or this page
http://www.embedtronics.com/nokia/fbus.html#part1

You need a list of hayes at commands to go alongside this here are the details

http://codeglobe.blogspot.co.uk/2009/02/at-command-set-for-sony-ericsson.html

or this page

http://www.developershome.com/sms/smsIntro.asp


Details of zigbee can be found here
http://www.zigbee.org/

Tod's idea is quite a good one as well just had a look that quite interesting

didn't i see trail cameras that sent email when they detected motion? as posted, it is going to get expensive.