Cisco CME and ephone Button Command attributes
: Normal Ring
b Call waiting Beep No ring
f Feature Ring
m Monitor mode
o Overlay Line no call waiting
c Overlay Line with call waiting
x Overlay expansion /Roll over
s Silent Ring
w Watch mode
Button Number (Attribute ) Directory Number
For Example if we have to configure one line when call comes there are silent ring on button no 2 and ephone-dn 10
#button 2 s 10