Apologies for the delay,been busy this end and for the life of me I cannot figure out how to get an image onto this board
(perhaps some kind soul will read this and drop me a line)
And no I dont mind answering questions we all have to start somewhere, there are some topics that are a complete mystery to me.
In answer to your last question - Yes
The dtmf is constanly listening for those specific tones and ignores everything else.
Anyhow managed to find the circuit you are going to build and have figured out a solution. Have posted 2 sdrawings at the following location
https://groups.msn.com/SciFiHeaven/shoebox.msnw
One is for a 4 digit lock the other is a rough sketch of your circuit with some suggested modifications.
A rough explination of the changes is this;
the output of the DTMF is inverted through a 4049 before being passed to the decimal decoders, both recieve the same input but only one is selected as active, this device provides the input to the lock circuit,use wire links to choose four numbers 0 - 9 (can only use each number once) and connect in the desired sequence to lock circuit ABCD the unused numbers get connected to the reset pin.
When you call the phone line the phone will continue to ring until your code is entered and the lock circuit changes state,this change triggers a 555 timer in monostable mode (how long a delay is up to you), it is this output that does two things.
It activates the transistor driving relay 1 to silence the phone and switches over to the second decoder that controls the latches that drive the control relays. ( you now have ten