Discontinued by Avaya.  The 10U100 headset is no longer available.  If you still need a wireless headset for your Partner telephone, you now have 2 options (click on the link below):

ALTERNATIVE HEADSETS OPTIONS:

• Replaced by the Plantronics CT12 -
  • Similar to the 10U100, plugs into the auxiliary port of the Partner phone.  Do not order this headset if you don't have a auxiliary port on your Partner phone. For detail operating instructions, see the CT12/10U100 user guide.
  • NOTE: The CT12 will work the same as the 10U100. The only difference is that the CT12 is not labelled with the "Avaya Logo".
• Replaced by the Plantronics/Avaya AWH-54 -
  • This is a totally wireless headset system.  There is no belt clip (battery pack) to carry with you. 
  • NOTE: The AWH-54 does not perform any functions such as transfering or putting calls on hold/park. You must be at your desk to perform all of those functions. (or the Avaya AWH54 + HL10 if you need remote answering capabilities) -