Milliwatt() — Generates a 1,000 Hz tone
This application generates a constant 1,000 Hz tone at 0 dbm (μlaw). This application is often used for testing the audio properties of a particular channel.
; generate a 1000HZ tone
exten => 123,1,Milliwatt()
Please note that there is a service that the carriers use to
test circuits for loss, that folks in the industry have nicknamed
“1,000-cycles.” The thing is, the tone the carrier equipment sends
is actually 1,004 Hz, so if you want to test circuit loss on an
analog channel from Asterisk, Milliwatt() may not give you exactly
what you want.