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I need VB.NET functions to detect when a phone is off-hook (meaning, a user has answered the phone or is placing a call), and to record the audio on the line until the hangup event is detected.
I need this to work with a USB Modem (don't know which types of modems supporting line hook detection).
When a handset picks up the line, there is a voltage drop. The modem will need to monitor this voltage drop, and then pick up the line and begin recording. There may multiple handsets that can pick up on the same line. The modem needs to detect when all the handsets have hung up, and then stop recording.
Special drivers may be needed for the modem.
Milestone for proving the line/hook/voltage detection is required.