yes there is sounds like you have either dil 1 to 1.. or ddi
Description The Direct In Lines (DIL) 1:1 feature allows incoming outside calls
to be directed to a specific extension. When a CO line is assigned
as DIL 1:1, it is necessary to assign the destination. These
programs specify the extension number for day or night mode.
Selection • CO line number: KX-TD816 – 01 through 08, ( * =all CO lines)
KX-TD1232 – 01 through 24, ( =all CO lines)
• Extension number: 2 through 4 digits / Disable (no DIL 1:1)
Default All CO lines – Disable — Day / Night
Programming 1. Enter a program address (407 for day or 408 for night).
Display example: DIL 1:1 Asn Day
2. Press sp phone.
Display: CO Line NO?–> * = all lines or
3. Enter a CO line number.
To enter CO line number 01, you can also press sp phone.
Display example: CO01

isable
4. Enter an extension number.
To change the current entry, press CLEAR and the new number.
To disable DIL 1:1, press CLEAR.
5. Press autodial/STORE.
6. To program another CO line, press NEXT or PREV, or
SELECT and the desired CO line number.
7. Repeat steps 4 through 6.
Conditions • In the case of KX-TD1232, CO01 through CO12 are for the Master
System and CO13 through CO24 are for the Slave, if available. CO
line numbers in the out-of-service system are unacceptable.
• To assign all CO lines to one selection, press the key at step 3. In
this case, the display shows the contents programmed for CO01.
• You set the extension numbers in program [003] “Extension Number
Set,” ISDN extension numbers in program [012] “ISDN Extension
Number Set” and [017] “TD286 Extension Number Set,” voice mail
extension numbers in program [127] “Voice Mail Extension Number
Assignment,” phantom extension numbers in program [130] “Phantom
Extension Number Assignment” or floating numbers of pagers in
program [813] “Floating Number Assignment.”
• If a CO line is also programmed for DIL 1:N in program [603]–[604]
“DIL 1:N Extension and Delayed Ringing — Day / Night,” it is
regarded as a DIL 1:1 line.
in your case you will need to clear all lines this will give the lines back to the dil 1:n settings