Which of the following is not a standard used for paging system?

POCSAG
ERMES
IS-95
FLEX

The correct answer is C. IS-95.

POCSAG (Public-Cordless-Telephone-Service Access with Message Announcement by Coded SHell) is a digital paging system that uses a two-tone-multi-frequency (TDMA) modulation scheme. It was developed in the United Kingdom in the 1970s and is now used in many countries around the world.

ERMES (European Radio Message System) is a digital paging system that uses a time-division multiple access (TDMA) modulation scheme. It was developed in Europe in the 1980s and is now used in many countries around the world.

FLEX (Flexible Low-Rate Enhanced Data Service) is a digital paging system that uses a time-division multiple access (TDMA) modulation scheme. It was developed in the United States in the 1990s and is now used in some countries around the world.

IS-95 (Interim Standard-95) is a digital cellular telecommunications standard that uses code-division multiple access (CDMA) modulation. It was developed in the United States in the 1990s and is now used in many countries around the world.

However, IS-95 is not a paging system. It is a cellular telecommunications standard.