Handset constantly display missed calls

8.Handset settings8.1To set the handset ringtoneYou can set different ringtones for external calls and internal calls.Select from 20 handset ringtones.You will hear a sample ring as you scroll to each ringtone.Press Menu, scroll1.2.Set Handsetis highlighted. Press Select.Ringtoneis highlighted. Press Select.3.UD4. ScrollorUD5. Scrollorn6. Pressto return to standby mode.8.2To set the handset ringer volumeThe handset has 5 ringer volume settings plus Off.If the volume is set to Off,Press Menu, scroll1.2.Set Handsetis highlighted. Press Select.DRinger Volume3. ScrolltoUD4. Scrollorn5. Pressto return to standby mode.NotesWhen the phone is ringing, you may presscall.When the handset is in standby mode press and holdpress and hold*8.3To set the receiver volumeThis sets the standard volume level for the handset earpiece or hands-free.There are 8 levels to choose from.Press Menu, scroll1.2.Set Handsetis highlighted. Press Select.DReceiver Vol.3. ScrolltoUD4. Scrollorn5. Pressto return to standby mode.Handset settingsDSettingsand press Select.totoExternal Callorto the ringtone that you want and press Select.icon is displayed

It may be that your battery is flat or that you have missed calls or even that it is in use. It depends on the handset make and model

This sounds like a registration problem, the handset(s)
and the base have lost identification with each other.

I. To address this, first de-register the handset(s) ---
do this procedure for each handset:

0. Start by taking off the battery compartment cover....

1. press [menu]
2. scroll up/down to "Settings"
3. enter * 7 8 9 0 #
4. scroll down to "next page", press [select]
5. scroll down to "Register Clear?", press [select]
6. display asks "Confirm?" or "Register Clear??", press [select]
7. display reads "Ok" and chirps, press [ off ]

8. UNPLUG THE HANDSET BATTERY (why the cover was off)

9. Wait ~30 seconds, re-connect the battery & replace the cover

10. display reads "Not Registered" ===============================

II. To register the handset to the base:

1. press [Find Handset] on the base and hold for
~4 sec until the "In Use" lamp lights.
2. press # on the handset and set the handset into
the handset cradle on the base
3. within 30 seconds or so, the handset will either
chirp and display "Handset Registered", then
"Handset #1" or it will say "Registration Failed".

NOTE: the battery must be well charged prior to the
registration process, a weak battery may cause a
"Registration Failed". Charge the battery for a few
hours and try the registration ( II ) again.

NOTE: the base can only handle 5 handsets and will
increment the number of each handset registered
until "Handset #5" has appeared, even if some of
the handsets are lost/not in use. Trying to register
more than 5 handsets will result in "Registration Failed."
===============================

III. To clear the base of all handset registrations and
be able to start registering again at Handset #1:

1. press [Find Handset] on the base and hold past ~4 sec when the "In Use" lamp lights, at
about 10 secs the "In Use" lamp will begin to
blink.
2. release the [Find Handset] button momentarily,
then briefly press it again. After a moment,
all handsets that were registered to the base
(if any) will display "Not Registered" and be
ready for fresh registration
3. for multiple handsets, return to II. above and
register each handset in turn.
===============================
Good luck !!

• 1. In standby mode, press (intercom).
  • • Intercom is established immediately if there are only 2 registered handsets.
  • • If there are more than 2 registered handsets, the handset numbers which are available for intercom will be displayed.
• 2. Press the handset number you wish to call or press * to call all handsets.
• 3. Press (Talk) on a called handset to answer the internal call, where both internal callers can talk.
• 4. To end the intercom call, press (End/off) on either handset.

Registration:
Instructions if you need to register handsets to the base:
You can register additional handsets to have up to five handsets per base unit, with each handset's number (1 to 5) shown on its display.
1. Press and hold <PAGE> on the base station for more than five seconds to put the base station into registration mode. (Note: there is no feedback to know it is in reg mode.) It will stay in registration mode for about 1 minute. So complete following sequence within this time. (It helps if handset is kept very near to the base during this).
2. Press <MENU> and <UP/DOWN> on the handset to select REGISTRATION.
3. Press <OK> and you are requested to enter the 4-digit system PIN.
4. Enter the 4-digit system PIN.
5. Press <OK> to confirm, and the display will show SEARCHING. If the handset registration is successful, you will hear a confirmation tone and the <antenna icon> will stop flashing. This may take a short while. The handset will automatically be allocated the next available handset number. This handset number is shown in the handset display in standby mode. If thehandset registration is unsuccessful, the <antenna icon> will still flash and the display will return to ' REGISTER', so you will need to repeat registration process.

October 10th, 2013 at 9:19 amPROBLEM:
After de-registering handset, handset displays [REGISTRATION FAILED; UNAVAILABLE] when trying to register handset.
This worked for my UNIDEN TRU-9480-2
SOLUTION:
1) Remove handset from base
2) Remove power cord from back of base
3) Press and hold the [find hs] button on base as you plug the power supply back in; the charge light should then be blinking.
4) Return handset to base and it should register
GOOD LUCK!! HOPE THIS HELPS!!

you can contact the service provider...........

HOPE THIS HELPS:
Call Forward • The first handset (HS1) can forward an external call to another handset (HS2, HS3, or HS4) by pressing and holding the INTERCOM key. After entering the handset number to which you want to forward the call, HS1 will display CALL FORWARDED. • To answer the call, another system handset can press PHONE, SPEAKER or any dial pad keys.
NOTE: If the other HS2 does not respond within 30 seconds, the external call will be returned to HS1 and its display will show CALL BACK. If the returned call is not answered within 30 seconds, the external call will end automatically
THE MANUAL CAN BE FOUND HERE: http://dl.owneriq.net/c/c72cee7d-bd52-42c1-b9fa-2ee5ccc500af.pdf

The process is called "Registering."

From another fixya post:

1. Make sure to charge the handset battery pack at least 12 hours.
2. Using the soft keys on the base located below the base screen, press MENU.
3. Use the up or down arrow keys to select DISPLAY BASE ID.
4. Press OK. The base screen will display the 15-digit Base ID
code for about 30 seconds, then the unit returns to the idle
screen. Write down the Base ID code on a piece of paper.
5. At the cordless handset, use the soft key to select NEW.
6. Enter the 15-digit Base ID code using the number keypad.
7. Use the soft key to select OK. The screen displays PLEASE
WAIT!.
8. After about 45 seconds, the screen displays FOUND BASE. If the handset displays BASE BUSY TRY LATER, the base is in
use.

hi just want to help others as desciption aint complete above

Registering a BT Freestyle 2200 handset
1. If there is a handset in the base remove it whilst you are registering the new handset.
2. Press and hold the PAGE button on the base for about 10 seconds until you hear a beep and the In Use light starts flashing.
3. On the handset to be registered, press and hold redial & CALLSd buttons together until display shows 65-.
4. Enter the base number. If this is a new handset then the base number is 1, the display shows 65-1 then PIN. which is normally 0000
5. Enter and registration starts. When the handset beeps and returns to standby registration is complete.