This is a read-only integer, in dBm, reporting the current signal level being sent out to the telephony interface for this call leg. An admin monitors this to verify the gateway is transmitting audio at an appropriate level, since levels that are too low or too high toward the telephony side can cause complaints of quiet or distorted audio. For example, if users on a specific trunk report the outgoing audio sounds too quiet, an admin would check this level to see if the gateway is under-driving that telephony interface.