Oluwashina GSM: Global system for mobile
communications

PMB: Per munite billing

SIM: Subscribers identification module

DC: Direct current

BAIC: Barring of all incoiming calls

IDD: International direct dialling

PIN: Personal identification number

BI: Basic information

OSS: Operation and support sub-system

HLR: Home location register

SMS: Short message service

ISDN: Integrated service digital network

PC: Personal computer

PUK: PIN unblocking keys

PTC: Private telecommunications center

MRF: Mobile radio frequency

IMEI: International mobile equipment identity

CUG: Close users group

MCC: Mobile country code

CW: Call waiting

PSB: Per seconds billing

MMS: Multimedia message service

WAP: Wireless application protocol