Found one called Pinpointpal, although expensive it uses all 4 networks and is free for the first 2yrs then 25quid there after. Annnnnnnd it's British!!
You can use a old/cheap mobile phone to do the same thing long as its got GPS,saw one rigged up in an Mk5 transit located right under the dash permanently left on,you can track any mobile as long as its on and you know the number(google has loads of info)dont know about using all networks though.
But beware thieves are wise now with the use of GPS blockers