phone erlang

-module(phone).
-export([start/0]).
-export([idle/0]).
-export([call/2]).
-export([off_hook/1]).
-export([off_hook/2]).
-export([on_hook/1]).
-export([billing/1]).
-export([connected/1]).
-export([ringing/1]).
-export([start_tone/0]).
-export([start_ringing/0]).
-export([stop_ringing/0]).
-export([billingCreate/0]).
-export([billingList/0]).
-export([billingAdd/2]).


call(Pid, Number) ->
    Pid ! {Number, incoming}.

off_hook(Pid) ->
    Pid ! off_hook.

off_hook(Pid, Number) ->
    Pid ! {Number, off_hook}.

on_hook(Pid) ->
    Pid ! on_hook.

billing(Pid) ->
    Pid ! billing.

start() ->
   billingCreate(),
   spawn(phone, idle, []).

idle() ->
    io:fwrite("Telefon czeka na polaczenie!~n", []),
    receive
        {Number, incoming} ->
            start_ringing(),
            ringing(Number);
        off_hook ->
            start_tone(),
            dial();
        billing ->
            billingList(),
            idle()
    end.


ringing(Number) ->
    io:fwrite("Oczekuje na odebranie!~n", []),
    receive
        {Number, other_on_hook} ->
            stop_ringing(),
            idle();
        {Number, off_hook} ->
            stop_ringing(),
            connected(Number)
    end.

connected(Number) ->
    billingAdd(Number,"Rozpoczecie rozmowy"),
    io:fwrite("Polaczono ~n", []),

    receive
        on_hook->
            billingAdd(Number,"Zakonczenie rozmowy"),
            idle();
        _ ->
            connected(Number)
    end.

dial() ->
    io:format("Tryb laczenia...~n"),
    receive
        on_hook ->
            idle();
        {Number, off_hook} ->
            connected(Number)
    end.

start_tone() ->
        io:fwrite("Laczenie...~n", []).

start_ringing() ->
        io:fwrite("Telefon dzwoni!~n", []).

stop_ringing() ->
        io:fwrite("Telefon przestal dzownic!~n", []).



billingCreate() ->
    ets:new(billing, [public,duplicate_bag,named_table]),
    ets:insert(billing, {"Phone","Podlaczenie telefonu"}).

billingList() ->
    erlang:display(ets:lookup(billing, "Phone")).

billingAdd(Number,Action) ->
    ets:insert(billing, {"Phone",Number,Action,erlang:localtime()}).