This sets the transmit power level, in the object's defined units, of the high-frequency tone component used for incoming-call line signaling on this trunk. R2 CAS uses a two-tone, high/low frequency, signaling scheme, so this power level directly affects whether the far end's tone detector reliably recognizes incoming signaling; set too low and weak signaling can be missed on a noisy or attenuated line, set too high and it can overdrive the receiver. On a trunk with unusually high line attenuation, an admin might raise this value from its default to ensure the high-frequency component of incoming signaling stays reliably detectable at the far end.