Polycom SoundStructure C16 Design Manual page 148

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
Line Voltage and Loop Current
The line voltage and loop current are active whenever the Poll Telephony
Information is enabled at the top of the user control. The line voltage and loop
current allow for diagnostics of the telephone line. See Appendix A of this
manual for more information on how to query the line voltage and loop
current values.
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