What is a SCM: Station Class Mark?

The SCM (Station Class Mark) is a 4 bit number which holds three different pieces of information. Your cellular telephone transmits this information (and more) to the cell tower. Bit 1 of the SCM tells the cell tower whether your cellphone uses the older 666 channel cellular system, or the newer 832 channel cellular system. The expansion to 832 channels occured in 1988. Bit 2 tells the cellular system whether your cellular telephone is a mobile unit or a voice activated cellular telephone. Bit's 3 and 4 tell the cell tower what power your cellular telephone should be transmitting on.

Bit 1:
0 == 666 channels
1 == 832 channels

Bit 2:
0 == Mobile cellular telephone
1 == Voice activated cellular telephone

Bit 3/4:
00 == 3.0 watts (Mobiles)
01 == 1.2 watts (Transportables)
10 == .6 watts (Portables)
11 == Reserved for future use

CDMA Station Class Mark

In CDMA, the Station Class Mark is an 8-bit number with a wider range of options than in traditional analog cellular networks.

Function	Bit(s)	Setting
Extended SCM Indicator	7	Band Classes 1,4: 1 Other bands: 0
Dual Mode	6	CDMA Only: 0 Dual Mode: 1
Slotted Class	5	Non-Slotted: 0 Slotted: 1
MEID support indicator	4	MEID not configured: 0 MEID configured: 1
25 MHz Bandwidth	3	Always 1
Transmission	2	Continuous: 0 Discontinuous: 1
Power Class for Band Class 0 Analog Operation	1-0	Class I: 00 Class II: 01 Class III: 10 Reserved: 11