S38 – cadence a max off time of dial tone, S39 – cadence b min on time of dial tone, S40 – cadence b max on time of dial tone – Maxim Integrated 73M2901CE AT Command User Manual

Page 33: 42 s41 – cadence b min off time of dial tone, S42 – cadence b max off time of dial tone, S43 – cadence a min on time of busy, S44 – cadence a max on time of busy, S45 – cadence a min off time of busy, S41 – cadence b min off time of dial tone