Which digital modulation method is used to transmit caller ID information on analog FXS ports on
Cisco IOS routers?

A.
DTMF

B.
PSK

C.
FSK

D.
MF

E.
pulse dialing

Explanation:
Link:-http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/vcr1/vcr1-cr-book/vcr-c4.html