What is the meaning of prefixes like DZ, DM, IZ, etc.?

When a recipient receives a message from any provider or bank etc., a sender ID along with a prefix is displayed in the inbox. For example- VM-ICICIB, BW-Google, DM-Amazon, VM-Redbus, etc.

The prefixes VM, BW, etc. are displayed because SMS is sent in huge numbers via bulk SMS. SMS providers follow rules framed by the Telecom Regulatory Authority of India (TRAI) and according to TRAI rules

• Sender ID should be restricted to 6 characters. (E.g MM - MSGIND) 

• The prefix has a specific meaning. That is:
  

• The first character of the prefix displays the operator name
  

  Operator	Code
  Aircel, Dishnet Wireless	D
  Airtel	A
  BSNL	B
  BPL Mobile/Loop Telecom	L
  Idea Cellular	I
  MTNL	M
  Reliance Communications	R
  Reliance Telecom	E
  Tata Teleservices	T
  Unitech	U
  Vodafone Videocon	V C & Q

  The second character represents the location of the operator through which the message is received: 
  

  Operator	Code
  Andhra Pradesh	A
  Assam	S
  Bihar	B
  Delhi	D
  Gujarat	G
  Haryana	H
  Himachal Pradesh	I
  Jammu & Kashmir	J
  Karnataka	X
  Kerala	L
  Kolkata	K
  Madhya Pradesh	Y
  Maharashtra	Z
  Mumbai	M
  North East	N
  Orissa	O
  Punjab	P
  Rajasthan	R
  Tamilnadu	T
  UP-East	E
  UP-West	W
  West Bengal	V

• Therefore, if you get a message like MM-MSGIND, you can interpret that you've got the message through the MTNL operator from Mumbai.