Trying to register used handsets

Please refer page 31 in the attached manual for registering handsets to base unit. Good luck.

http://service.us.panasonic.com/OPERMANPDF/KXTG6511-MUL.PDF

Yes. The'old' handset must be de-registered from its
original base and then registered to your base.

NOTE: the CS6229 handles a maximum of 5
handsets. If you have a handset displaying
"Handset #5" then you have a 'fully populated system'
even if you actually have only one or two handsets.

You will need to clear each handset ( I ) then clear
the base of all registrations ( II ) before re-registering
each handset ( III ) up to the maximum of five.
=====================================
( I ). First, to de-register a 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
(this is why the cover was off)

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

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

( II.) To clear the base of all handset registrations
( if needed, else skip ahead to ( III ). )

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 ===============================

( III.) To register each 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 #x" 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 ( III ) again.

===============================
Good luck !! --

According to the manual starting on page 52, you need to de-register all handsets then re-register the handsets one at a time. The manual covers both cordless model numbers so the handsets should be interchangeable. I have included a link where you can download the manual if you need it.

http://att.vtp-media.com/ecp/documents/product_Product/127/UserManual/1082/cl82209_manual_i3.pdf

Press (menu 00, reg) an press locator for 3 secons--- than press ok in you phone.

Short answer:
No. This model of phone can only support 4 handsets. If you need more than that, you will need to have a second base unit.

Detailed answer:
One of my handsets went bad, and I just bought complete DCT748-4 package from a seller on eBay for a very good price. This set was used, but in very good condition. I didn't need the whole set - just one handset - but like I said, it was a good price. Anyway, I began by telling my old base unit to de-register handset #2 (the failed unit). However, I then found that I could not register the "new" handset with my old base unit because it was already registered to the "new" base unit. So, I first had to apply power to the "new" base unit and de-register the handsets. Then, I placed one of the "new" handsets onto my old base unit, and it said "Handset Registering ..." and registered just fine. Just for the fun of it, I placed one of the other spare handsets into my old base unit. It said "Hanset Registering ..." but then it beeped and said "Registration Failed." This is because I already had 4 handsets registered to my base, and the base can not handle a fifth handset.

First, deregister all handsets:

Step 1: At the base, press MENU, scroll to BASE SETTINGS, then press OK.

Step 2: Using the base dialpad, enter * * 3 3 5 7 8 2

Step 3: Re-register each system handset:

At the base, press MENU, scroll to DISPLAY BASE-ID, then press OK. The 15-digit base ID number will be displayed.

Step 4: Using the handset dialpad, enter the base ID number. Repeat the registration procedure for each system handset. Each handset is assigned a number in the order of registration

1. Delete or listen to all voice mail messages, if necessary, to clear the IN USE/Voice Mail light indicator.
Note: Skip this step if it does not apply to your MD Series cordless telephone model.
2. Press OFF on the base station and each handset.
3. Press and hold down PAGE on the base station until the IN USE light flashes slowly, then release.
4. Press and hold down PAGE again until the IN USE light begins to flash quickly, then release PAGE.
5. Quickly and fully press and release PAGE again.
6. Please register handset displays. Press OK to begin the registration process, or press EXIT.

This exact thing happened to me. Same model number. No matter what I did, the new handsets would not register.

The solution? Reset the entire system:
1. On the BASE - Unplug from wall both power and phone line. Unplug battery from base handset.
2. ON the Extension phone - unplug from wall and unplug battery from handset.
3. Wait AT LEAST 5 minutes.
4. Plug back in BASE power.
5. Plug back in BASE phone line.
6. Plug back in EXTENSION handset battery. Don't plug in BASE handset yet.
7. Follow steps to program EXTENSION. When successful:
8. Plug back in BASE handset battery.

I believe you have the expansion capacity of the phone all used up. The phone cannot register any more handsets until you delete the handset registered that is not in use. First check the handsets and see what handset numbers they carry. It should be #1,#2,#3,and #4 if it does not then you will have to delete the one that is missing or if it is then delete handset #5.To do this you will have to use one of the handsets registered to the base. First Press the MENU/ OK button then scroll down to ADV,SETTING then Press MENU/OK then scroll down to DEREGISTER then Press MENU/OK. Then ENTER HANDSET PIN would show, if you have not changed the pin enter 0000 if you have enter your pin member. From the next options select HANDSET and press MENU/OK from the next set of options select the handset number you want to DEREGISTER and press MENU/OK from the next option select YES then MENU/OK. Then try to reregister the new handset To do this Press the MENU/OK button then go to ADVANCE SETTING press MENU.OK scroll to REGISTER then press MENU/OK Select the base number displayed then press MENU/OK. PLEASE WAIT will appear. Then from the base press and hold the PAGE button until the handset prompts you to ENTER PIN # .Enter 0000 OR your pin number then you will see PLEASE WAIT. A tone will confirm the handset registration.

USer manual requires,
full charge 16 hours for expandable handsets, then place in cradle ~20 seconds until 'ready' is displayed on the screen.
If power is lost the handset may have to be re-registered.

if the units are not fully charged when you register them the registration may be lost, can only suggest reversing the order, by fully charging the device then registering to see if the registration holds