How to dereigster an orphaned EL52203 handset to be able to register with my base

Success! - yes, the video you linked worked (the key being entering *7890# while in settings). I've written the process down here for others:

How to reset/deregister an EL50003-family handset to re-register with base.

For here: M/S = menu / select button (upper right)

1) M/S, scroll to SETTINGS, M/S
2) Enter *7890#
3) Scroll to TEST HANDSET, M/S
4) Scroll to NEXT PAGE . . ., M/S
5) Select REGISTER CLEAR, M/S, M/S
6) Display shows OK meaning successfully reset.
7) Use OFF button to get back to main display which will flash “to register HS...”.
😎 Place on base, will say Registered after 15 sec or so.

Source: https://www.youtube.com/watch?v=NCHSuoOzDMQ

This works on many different makes and models of cordless handsets. 

At the handset(s) do the following

*331734# followed by menu/select

The phone beeps twice, reboots and then comes back up ready to register to a new base station.

Registering to the new base station is now accomplished using the standard instructions.

Sadly does not seem to work for these - tried multiple times.

You're the first to say it didn't work, so all you can do is start searching the Internet.  I did find a video here that uses a different sequence that may work.  Just in case you missed it you did put a star * prior to the numbers, correct?

Thank you for posting the steps, I'll bookmark this one.

Need info on model EL52301, no response pressing menu/select.

I've gone through the steps to deregister my new handset twice and it is still giving me the "out of range or no power at base" message.

I'm trying to pair a replacement el52300 handset and base with an el52400 system.

I've also tried the *331734# but when I press the m/s button the phone doesn't beep and says "edit number"

Any help would be much appreciated.

What handset and did you check to see if the two were compatible?

@spoom2 The new phone is Model el52300 (what it says under the battery cover) and trying to pair it with the el52400 system. When I looked it up on the AT&T website for compatibility it says the page is no longer available. When I look up both phone systems user manuals I get the same exact one so I'm guessing they are compatible. Also, both phones look exactly alike.

*I was able to get the phone to work. Unplugged the battery and plugged it back in. Instantly was able to register to my phone system.

For spoom2:

Many thanks for all your help.  The *331734# code worked fine for 2 handsets I had bought separately for an "ancient" SL 81028 series set.  AT&T led us back to you, so don't leave the country!

Thanks again,

Roger 

The method given above, "*331734# followed by menu/select" worked to allow me to register a used phone I bought to add to my system.  

Thank you.