i have just purchased a gps tracker for my caravan (no jokes please!) it works by me sending a coded text to the device and it then in turn texts me back the gps co-ordinates which i then put into google maps to get the exact location SIMPLE! problem is it texts me back 'GPS INVALID' after further reading of the instructions i find 'In some circumstances with high end 3G or gprs phones the text message transport system is not compatible with simple peer to peer text messages. In which case a simple mobile phone will have to be used to establish gps location.' WHAT! i dont have a simple one i have a htc legend anyone know how i can do it? an app perhaps?