SMS Sender Ids

Prefix: A prefix in SMS Messages are the first two characters in the Sender ID. The first alphabet represent the name of the operator and the second alphabet represent the location. A Sender ID is the address of the Sender. With the help of a Sender ID we can easily make out from where we are receiving those messages.
TRAI (Telecom Regulatory Authority of India) enforced regulations because of which when any company or working body which sends bulk SMS need to register with a unique ID, also called as Sender ID.
Telecom Commercial Communications Customer Preference Regulations (TCCCPR) 2018 provides for assigning alpha-numeric headers to Principal Entities (Business or legal entities) for the purpose of sending Commercial Communications via Short Message Service (SMS).
Headers / Sender ids are assigned by a TSP (Telecommunications Service Provider) to the Principal Entity to identify itself while sending messages to the subscribers.
As on date these headers are prefixed by two alpha characters separated by a hyphen from the header and it is used to identify OAP(Originating access providers). Currently fixed length of six alpha-numeric characters are being used to assign headers and total nine characters including prefixes and separator are being used. Headers are also known as Sender ID.

Typical format and structure of the header with prefixes is as below:
XY-ABCDEF
X denotes TSP (OAP);
Y denotes License Service Area (LSA of OAP)
ABCDEF is a header assigned to the Principal Entity

Source: https://www.trai.gov.in/sites/default/files/Detail_Header_Prefixes_16062020_0.pdf

SMS delivered by TSP: Airtel Karnataka -JoinIndia Technological Solutions Limited

SMS delivered by TSP: JIO Kolkata -JoinIndia Technological Solutions Limited

SMS delivered from TSP: Airtel Delhi -MissCallAlert

SMS delivered from TSP: JIO Delhi -Monster