Tone/Code

A sub-frequency or subaudible tone is added to the transmission frequency,
so that receivers will only respond to transmissions with the same
frequency and tone.

PL = Private Line

CTCSS = Continuous Tone Coded Squelch System (67-254Hz)
49 Subaudible Tones in Hz:
67.0, 69.3, 71.9, 74.4, 77.0, 79.7, 82.5, 85.4, 88.5, 91.5, 94.8, 97.4,
100.0, 103.5, 107.2, 110.9, 114.8, 118.8, 123.0, 127.3, 131.8, 136.5,
141.3, 146.2, 151.4, 156.7, 159.8, 162.2, 165.5, 167.9, 171.3, 173.8,
177.3, 179.9, 186.2, 189.9, 192.8, 196.6, 199.5, 203.5, 206.5, 210.7,
218.1, 225.7, 229.1, 233.6, 241.8, 250.3, 254.1

DCS = Digitally Coded Squelch
104 Tones:
023, 025, 026, 031, 032, 036, 043, 047, 051, 053, 054, 065, 071, 072,
073, 074, 114, 115, 116, 122, 125, 131, 132, 134, 143, 145, 152, 155,
156, 162, 165, 172, 174, 205, 212, 223, 225, 226, 243, 244, 245, 246,
251, 252, 255, 261, 263, 265, 266, 271, 274, 306, 311, 315, 325, 331,
332, 343, 346, 351, 356, 364, 265, 371, 411, 412, 413, 423, 431, 432,
445, 446, 452, 454, 455, 462, 464, 465, 466, 503, 506, 516, 523, 626,
532, 546, 565, 606, 612, 624, 627, 631, 632, 654, 662, 664, 703, 712,
723, 731, 732, 734, 743, 754