Cell phones in gliders - tracking function

My GPS tracking phones I use to track my small fleet of trucks do not
show altitude. They only show location and speed and you can overlay
tracking on a map (on the web). Last weekend my track from Cal City
to Mt. Whittney and back to WJF & L71 showed up quite nice. The phone
receives GPS and every 15 min it sends via a cell call to a server the
phone position stored every 5 minutes. I can ping the phone and get
on demand location & speed if the phone can contact the cell site. If
the cell phone cannot contact a cell site it will store until it does
and than down load all stored points. If I had of landed out in the
Sierras it probably would do me no good except to show last position
tansmitted maybe in the air? If in the Valley it could come in handy
if incompasitated.