Uniden DCX300 Series - Manual (Page 6)

Installing the Optional Headset
Your phone may be used with an optional
headset. To use a headset, insert the
headset plug into the headset jack.
Headsets may be purchased by calling
the Uniden Parts Department. See the
back cover page for contact information.
Registering the Handset
You must register the handset to the base before you can use it.
Only one handset can be registered at a time. (If an accessory
handset has ever been registered to a base, you must reset the
handset before you can register it to a new base.)
To register to a DECT3080 base:
Place the accessory handset in the base. While the handset is
registering, HANDSET REGISTERING appears in the LCD.
When REGISTRATION COMPLETE is displayed, the handset
has been registered to the base.