I can talk for over 5 continuous hours on this headset (never tried longer).  However, my Motorola HS820 is more comfortable AND my callers understand me better.  I get many complaints with the Scala 700 that my voice isn't clear or our connection is bad.  In addition, when I listen to mp3 files, the HS820 has a warmer sound.  The Scala 700 has a 'tinty' sound.