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i got the current carrier 2 wire door intercom schematic

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hi all,

I got copied the circuit of commax door intercom.
Iam sending you the file which i copied by reading the PCB of Door Plate i.e the intercom which will be placed at the door side where the visitor will come and ring the bell by pressing the push button.

I have drawn this so called schematic using MS Word so there few bugs in drawing the schematic but i have tried my level best to make it in a easier way using direct components indication so that symbol problem does not occur .

Please see this circuit and please provide some guidance about using this circuit or what may be the possible working of this circuit. I think it uses two C945 for amplifier circuit.

Also there is a transformer in it on which JOT-S is written can you please guide me any way of finding out its value or something which can give me a idea about this..

My objective is first learn the circuit avaiable in market which works on 2 wires or current carrier type and then implement it suign LM386..

in the schmetic on top of page the wires going out of transformer are the one which will go in the intercom present inside the home now that circuit is hard to copy but i will make it if there occur any problem but to give you an idea that home intercom circuit contains a 9 Volts Supply , Ringer Circuit using some ICs which are i think made by commax company as they are not avaiable in market.

Using this schmatci please explain who this current carrier circuits are made using transformer isolation theory..
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