-Track a location from another phone by sending sms to a given number
-Encrypt the sms that are being sent to avoid leaking your location.
-Use Trackpa Receiver (https://play.google.com/store/apps/details?id=com.vaslabs.trackpa_receiver) that generates encryption keys and visualises the locations that are being received.
It is recommended that you have a package with unlimited SMS messages to avoid high costs.
Source code is available at: