This　paper　presents　information　on　an　autonomous　fall　detection　and　alerting　system　mainly　consisting　of　a　custom　vest　and　a　mobile　smart　phone.　A　3-axial　accelerator　and　gyroscope　with　a　mainboard　and　Bluetooth　are　built　into　a　custom　vest　worn　by　elderly.　The　vest　can　capture　the　data　about　the　activities　of　daily　living　(ADLs)　of　elderly　in　real　time.　The　data　via　Bluetooth　is　then　sent　to　a　mobile　smart　phone　equipped　with　a　threshold-based　fall　detection　algorithm　based　on　3-axial　accelerator　and　angular　velocity.　When　a　fall　occurs　the　phone　can　alert　a　family　member　or　health　care　center　through　a　call　or　an　emergent　text　message　with　a　built　in　global　positioning　system　(GPS)　location,　so　as　to　provide　a　fast　and　accurate　intervention.　The　experimental　results　show　that　the　system　discriminates　falls　from　ADLs　with　a　sensitivity　of　95.74%　and　a　specificity　of　88.75%,　for　a　total　set　of　175　movements