Hello all
I'm working on a ckt that is connected to the telephone line.The device should be powed by the line itself. The working of the ckt is like , when the telephone is off-hook, the device receives a dtmf sequence, and when it receives the device should respond another dtmf sequence .
The problem is , since the telephone is off-hook , the caller will hear this dtmf handshaking .. Now how to avoid this ?. one way is to connect the telephone through relay(s) operated by the ckt. but i suspect the telephone line cannot supply that much current , and also that is not a good idea..
Any other method to solve this problem
Thanks in advance.
Akg