Couple of months back, TRAI ( Telecom Regulatory Authority of India ) enforced regulations because of which when any company or working body sends a bulk SMS they need to register with a unique ID, also called as Sender ID which is 8 charachter length e.g AX-AIRTEL. However sometimes the code is too short to find out in detail but thanks to Prashant who has provided 2 lists from wihich you can find the details :
Service Provider Codes:
Service Provider ===>Code
Aircel, Dishnet Wireless ===>D
Bharti Airtel ===>A
BSNL ===>B
BPL Mobile/Loop Telecom ===>L
Datacom Solutions ===>C
HFCL Infotel ===>H
Idea Cellular ===>I
MTNL ===>M
Reliance Communications ===>R
Reliance Telecom ===>E
S tel ===>S
Shyam Telecom ===>Y
Spice Telecom ===>P
Swan Telecom ===>W
Tata Teleservices ===>T
Unitech Group ===>U
Vodafone Group ===>V
Service Area Code
Service Area ===>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
Tamil Nadu ===>T
UP-East ===>E
UP-West ===>W
West Bengal ===>V
In order to find out the origin of the sender id, just break the code into two to find region or sender. Though the above list might not cover all of them but you definetly have the idea why there was no number displayed.
BSNL ===>B
BPL Mobile/Loop Telecom ===>L
Datacom Solutions ===>C
HFCL Infotel ===>H
Idea Cellular ===>I
MTNL ===>M
Reliance Communications ===>R
Reliance Telecom ===>E
S tel ===>S
Shyam Telecom ===>Y
Spice Telecom ===>P
Swan Telecom ===>W
Tata Teleservices ===>T
Unitech Group ===>U
Vodafone Group ===>V
Service Area Code
Service Area ===>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
Tamil Nadu ===>T
UP-East ===>E
UP-West ===>W
West Bengal ===>V
In order to find out the origin of the sender id, just break the code into two to find region or sender. Though the above list might not cover all of them but you definetly have the idea why there was no number displayed.