Panasonic KX-TGM420 Operating Instructions Manual page 87

Storing a range of number
1 [MENU] [#] [2] [1] [7]
2 [ ]: "Block range of numbers"  [SELECT]
3 [MENU]  [
4 Enter the desired number (2-8 digits)  [SAVE] 
[OFF]
Blocking incoming calls that have no phone
number
You can block calls when no phone number is
provided, such as private callers or out of area calls.
1 [MENU] [#] [2] [1] [7]
2 [ ]: "Block unknown CID"  [SELECT]
3 [ ]: Select the desired setting [SAVE] 
[OFF]
]: "Add"  [SELECT]
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