SCM

SCM = Service Class Mark. It is a two digit number which dentifies some of your phones features for the cellular network. Power level, number of channels (666 channels for older AMPS phones, 832 for newer ones), and whether the phone is voice-activated.

Proper SCM Value       Attributes of Your Phone
 00             Standard power output; 666 channel cap.; no VOX operation.
 04             Standard power output; 666 channel capability; uses VOX.
 06             Low power output; 666 channel capability.
 08             Standard power output; 832 channel cap.; no operation.
 10             Low power output; 832 channel capability; no VOX operation. 
 12             Standard power output; 832 channel capability; uses VOX.
 14             Low power output; 832 channel capability; uses VOX.