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(g) TELNET (Remote Login)

Telnet is a remote login that helps a user to log on to another user’s terminal without
being its original user. A user who is logging in to their own system can also get access to
log on to another user system and perform various functions such as accessing files or
sharing files to/from the remote system. With TELNET, a user logs in as a regular user
with whatever privileges they may have been granted to the specific application and data
on that computer.
Working of Telnet

(i) A user is logged in to the local system and invokes a TELNET program (the TELNET
client) by typing telnet<host address> or telnet <IP address>

(ii) The TELNET client is started on the local machine (if it isn’t already running). The
client then establishes a TCP connection with the TELNET server on the destination
system.
(iii) Once the connection has been established, the client program accepts characters
from the keyboard feed by the user and passes one character at a time, to the
TELNET server.

(iv) The server on the destination machine accepts the characters sent to it by the client
and passes them to a terminal server.
(v) The terminal server gives outputs back to the TELNET server and displays them on
the user’s screen.

The user can terminate the telnet session by typing LOGOFF or LOGOUT on the system
prompt.

8.14 WIRELESS/MOBILE COMMUNICATION

8.14.1 GSM (Global System for Mobile Communication)

GSM stands for Global System for Mobile communication. It provides its subscribers with roaming
facility so that they can use their mobile phones all over the world to communicate with each
other. GSM provides digital signalling as well as digital call facility and is so considered as a second
generation (2G) mobile phone system. It provides consumers with better voice quality and low-
cost alternatives to making calls such as short message service (SMS). It has an ability to carry 64
kbps to 120 mbps of data rates. The key feature of GSM is the Subscriber Identity Module (SIM),
generally known as SIM card. It is a detachable smart card that contains the subscriber’s information
along the phone book. This allows the user to use the phone book and other information even after
Computer Science with Python–XII 8.34 8.14.2 CDMA (Code Division Multiple Access)
changing the handset.

CTM: GSM is a wireless communication medium that provides the user with roaming facility, good voice
quality, SMS, etc., through digital signals.

CDMA stands for Code Division Multiple Access. CDMA is an example of multiple access, where
several transmitters can send information simultaneously over a single communication channel.
It is a channel access method used by various radio communication technologies. It allows the