Panasonic KX-FT21RS - Manual (Page 80)

2.5.1. DTMF SIGNAL TONE TRANSMIT SELECTION
Note:
After performing this check, do not forget to turn the setting off.
Otherwise, dialing using DTMF will not be possible.
2.5.2. BUTTON CODE TABLE
Note:
These codes (00, 01) are only for the data in the History Report.
2.5.3. PRINT TEST PATTERN
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KX-FT21RS