XCRetrieve is a complete tool for SMS based GPS location sharing.
• let others find you when you can't answer the phone, they just need to text you with a defined code;
• easily share your position in in several common formats including a Google Maps link;
• view received locations on Google Maps or Open Street Maps;
• define a default contact to allow sharing or requesting their location with a single tap;
• works without internet access, no external services, just simple SMS based communication in human readable formats.

Get Started:
1. Install the app and go through a very short configuration wizard
2. Share the assigned code with your friends
3. Once you receive an SMS message starting with the code, your phone will attempt to get 2 GPS fixes with your coordinates and will send a response SMS message containing your last position, altitude, speed, direction and a movement index value. You can also add "-i" (without quotes) to the request, to get instant response, but without speed or direction heading.
4. The response text message is human readable. It doesn't need any utilities or services to decode, but if it is received by a device which also has XCRetrieve installed, a screen with information details and your position marked on a Google Maps will be displayed.

Primarily XCRetrieve was created with paragliding and hang gliding in mind, but will be perfect for most outdoor activities. XCRetrieve shares some concepts of "Where is my phone" apps or spying apps, but differs by some unique features:
• No text messages are ever deleted, this is not a spying app, you can always check who has requested your location, also no information apart from your location and accelerometer readings are shared.
• It can be used without internet connection and relies on SMS messages, as these are most reliable in areas with weak mobile network.
• It does send your altitude, which can make a big difference for aviation sports.
• Speed and direction is calculated based on 2 points fetched in a 60 second interval.
• A movement index value is sent (ranging 0-6) based on your accelerometer readings. This allows some rough estimation of what is happening with the phone and the user.

Offline usage:
Google Maps embeded inside this app will not work offline (even if you have downloaded a map for offline use). This is why OpenStreetMaps have been also included. They will display cached map areas when offline.

You can see a sample SMS request and response on the last screenshot.

Screenshots: