function hn=DTMF(num,a,b)phone='123A456B789C*0#D';fl=[697 770 852 941];fh=[1209 1336 1447 1633];fs=8000;N=80;for i=1:4    for j=1:4        d=(i-1)*4+j;        if phone(d)==num            nl=i;            nh=j;        end    endendwl=2*pi*fl(nl)/fs;wh=2*pi*fh(nh)/fs;hnn =DTMFn(a,b,wl,wh,N);hn=[zeros(1,360) hnn zeros(1,360)];