I had a set of d1484 and the base keeps showing a flashing 88,so I bought another set of the same serie. Can I use my old handsets with this new base?

Either the base is defective and not keeping the battery charged or the wall outlet or voltage adapter plug is defective.

If you want to replace a handset or re-assign the designated handset number of a registered handset, you must de-register all the handsets and then individually register each handset.
To de-register all handsets:
Press and hold
FIND HANDSET
on the telephone base for about 10
seconds (until the IN USE light on the telephone base turns on and starts to flash), then release FIND HANDSET
.
Press and release
FIND HANDSET again. (You must press FIND HANDSET
while the IN USE light is still flashing. The IN USE light flashes for
approximately seven seconds.)
All system handsets show
CONNECTING...
The de-registration process
takes about 10 seconds to complete. All handsets show
NOT REGISTERED
when the de-registration completes.
If de-registration fails, you might need to reset the telephone and try again.
To reset:
Pick up the registered handset and then press
/FLASH
.
Press
OFF/CLEAR
and place the handset back in the telephone base.
-OR-
Unplug the power from the telephone base, then plug it back in.
note:
You cannot de-register a handset if any system handset is in use.

After de-registering, proceed with registering process:
If the handset screen does not show LOW BATTERY
or HANDSET X, you will need to charge the handset for at least five minutes before registering to the telephone base.
To register a handset:
Place the unregistered handset in the telephone base or charger. If
PRESS FIND HS 4 SEC ON BASE
does not appear on the handset screen after a few seconds, remove the handset and place it in the telephone base or charger again.
On the telephone base, press and hold
FIND HANDSET
for about four seconds (until the red IN USE light on the telephone base turns on) and then release the button. The handset shows
PLEASE WAIT...
and it takes about 10 seconds to complete the registration. The handset shows
HANDSET X REGISTERED
(X represents the handset number assigned)
and you hear a beep when the registration completes.

If there is an error code with an E followed by a number or "88" displays/flashes it would be an internal issue in the base unit. Uniden does offer a limited 1 year warranty (Covers Manufacture Defects ONLY, if caused by a power surge or power outage or any other type of damage that is not a Manufacture Defect this is not covered under warranty) off the proof of purchase. The proof of purchase is required for warranty service.

when the battery cover comes off there are a series of microswitches that are visible.. make sure the new ones are set with your originals..

I just got off of the phone with Uniden for the same issue with my D1680-4. The alternating "8" - "88" code is an indication that the base is dead. They will be sending me a new base (and 2 handsets). During the call I learned that if you do not have a receipt, Uniden warrants their phones for up to 15 months. The advertised 12 months, plus 3 months for the product to get from manufacturing, through distribution channel and finally sale to the consumer.

On the Motorola L404 series, to deregister all handsets you unplug both the phone and power to the base station. Press and hold the 'find' button while plugging the power back in. The display will show "CL". Continue to hold the find button till the display shows '00' and all the handsets will show 'unregisterd'. You then proceed by registering all your handsets again in the order you want them listed.

hello there i think this is because you need to register the second handset with the base here are the instructions

REGISTRATION
Registration links the base to a cordless handset. Once a handset is
registered it can use the base’s phone connection. A cordless handset will
not operate until it is registered to the base. During the registration
process, keep the handset near the base.
1. Press the flash/program button on the base until LINK HANDSET shows
in the display. 2NO is the default setting.
2. Press the 1 number key or press the MESSAGES/CID (
or) button
on the base to scroll to 1YES.
3. Press flash/program to confirm handset is linked to the base. WAITING
HANDSET REGISTRATION shows in the display.
4. Press the flash/program button on the handset until LINK BASE? shows
in the display. 2NO is the default setting.
5. Press 1 on the handset keypad or cid/vol (
or) button on the
handset to scroll to 1YES.confirmation tone when the handset is successfully linked to the base.
6. Press flash/program on the handset again to confirm. You will hear a long

please leave rating if you find this usefull hope this helps thanx for using fixya!!

I ordered a new kx-tg560m handset for my kx-tg5632 base unit, but the enclosed instructions for registering it with the base unit were wrong. Fortunately, I found the old quick setup guide in my files.

If you do not have the same base unit and handset, go to the URL:
http://www.panaxonic.com/RegisterYourHandset.

1. On the handset, press [MENU], then press [0][0]. The handset displays "Refer to manual to prepare base. Then press OK->"
2. On the base unit, press [SELECT] until the desired extension number [H1, H2, H3, or H4] is displayed on the base unit, then press and hold [CALL] until the CHARGE indicator flashes.
3. On the handset, press the [OK] softkey.

When the handset is off and sitting in the charger, the handset's extension is displayed in the upper right corner.

Cancel the old handsets registration at the previous base unit if desired.
For additional handsets, you must register each of them at the new base unit. Only one handset can be registered at a time. A handset will be assigned anextension number at registration.

Make sure the base unit and the other handsets are not being used. Program the same way as the extra handset you bought.

Registration must be completed within 1 minute.

You need to reset the main base unit. Unplug the power from the back of the base. While the power is disconnected, press and hold the delete key while reconnecting the power. Wait for a long beep tone. When the display shows 88 or P, press play button one time. If you have a phone without an answering machine, disconnect the power from the back of the base, press and hold find hs button while reconnecting power.