I put new batteries in my At&T cordless phones and I am getting a message on phone screen T23 PD

To register a handset to your telephone base
Make sure the handset battery is installed and charged properly. You have to enter a 15-digit telephone base ID to register the handset to the telephone base.

To find the telephone base ID and register the handset:

1. On the telephone base, press the MENU softkey when in idle mode to enter the feature menu. Press the or softkey to scroll to the DISPLAY BASE-ID menu, then press the OK softkey. The telephone base ID will be displayed.

2. On the handset, use the keypad buttons to enter the telephone base ID and press the OK softkey.
Press the softkey to move the cursor.

3. The handset will first display PLEASE WAIT!!, then T23 PD followed by SEARCHING FOR BASE. The screen will finally display HANDSET X when the registration is successful.
NOTES:

1. If the registration is not successful, the display will show NO BASE SUBSCRIPTION. Try the registration process again.

2. If an incorrect base ID is entered, the base ID will disappear and ENTER BASE ID will be displayed.

In case of a problem or clarification or my solution was insufficient, don't hesitate to post me a reply.

If you are satisfied, rate my solution with the "thumbs" or (even better) add a testimonial.