Nextel phones are no longer available on Sprint.com
Sometimes the DuraPlus speakerphone was loud & clear, sometimes it was a useless whisper. The techs at the local Sprint corporate store tried & tried to make it work correctly, but on regular vouce calls in speakerphone mode, two handsets in a row were no good. Had to give up on the DuraPlus and reactivate the old phone (an i58sr that was about nine years in use, still works great).
Have you used your DuraPlus in speakerphone for regular voice calls?