Philips KX-TEA308 - Manual (Page 122)

2.1 Control Features
122 User Manual
To erase
PT/SLT
Off-hook. On-hook. Enter 722.
2 2 7
Enter 0. Enter #.
0
Dial common BV OGM
number (01–24).
C.Tone
common BV OGM no.
An SLT user can enter "0"
instead of "#".