Similar problem I have a similar problem on all 3 handsets.

Answer

How to stop the visual ringer blinking

That might be the Voice Mail Warning Indicator.
On the D3098 and similar handsets, it is reset by:

1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.

You might try to reset the Voice Mail Waiting Indicator ( V M W I ).

To reset the Voice Mail Warning Indicator
on the D1680 and similar handsets:

1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.

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

That might be the Voice Mail Waiting Indicator.
On the D1680 and similar handsets, it is reset by:

1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.

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

That might be the Voice Mail Warning Indicator.
On the D1680 and similar handsets, it is reset by:

1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.
Good luck!

That sounds like the Voice Mail Waiting Indicator.

On the D1680 and similar handsets, it is reset by:
1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.
Good luck!

This sounds like Handset #1 has lost its "registration" with
the base. De-registering & re-registering is often easy.

First, be sure the handset battery is well charged as a
weak battery will interfere with the registration process.
Then try this ( 'works for the D1680, D1481, & similar):

To deregister the handset:

1. Press and hold the [END] and [ # ] keys at the same time,
after a few seconds the display will say
"System Reset, Deregister Handset"
press [SELECT]
scroll to "Base Unavailable"
press [SELECT] (chirps) press [END]
display reads "Place in base..."

Next, to re-register the handset:

2. Set the handset into the base cradle and wait,
within ~30 seconds the handset should display
a "Handset #" and be good to go.

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

To reset the Voice Mail Warning Indicator ---
(( On the D1680 and similar handsets ))

1. press [menu]
2. scroll down to "Global Setup", press [select]
3. scroll down to "VMWI Reset", press [select]
4. scroll down from "No" to "Yes", press [select]
5. handset will chirp, blinking lamp goes out,
6. press [END]

Other models, check your manual. The model number
is on a small sticker under the battery in the handset --
enter this number at www.manualslib.com to get a free
copy of the User's Manual.

Good luck!

I have similar model and setup should be the same..
1, Handset: press Menu
2, Handset: scroll using up/down arrow keys to "Initial setting" then press soft key Select
3, Handset: scroll to "Registration" press soft key Select
4, Handset: sroll to " HS Registration" press soft key Select
5, Base Unit: Press and hold (LOCATOR/INTERCOM/TRANSFER) for 3 seconds. The Charge indicator flashes. After the CHARGE indicator starts flashing, the rest of the procedure must be completed within 1 minute.
6, Handset: 1: press soft key OK
2: wait untill a long beep sounds and the display shows the new extention number
**Registration should be complete**

Here are a couple things you can try.

Clean the charging contacts, this can be done two ways. The manufacture's recommend using a pencil eraser. I recomend using a q-tip and some rubbing alchol. Just rub the alchol soaked q-tip on all the metal contacts on the bases and the bottom of the handset.

Gooo luck.
Hope this helps

i faced a similar problem.try doing this
1) go to handset menu & somewhere u wil find registration
2)it wil ask for pin , try 5555 or 0000
3)it wil display waiting for reg or searching......
4) press the base station button for some 5 seconds until it beeps continuosly & stops....
5) as beep stops press 1 or 2 or 3 or 4 in handset ( no. of hanset handled by base)...try all possibilities ( sometimes takes automatically if u dont press any number)
6) thats it.......
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