SMS Sender Code/ Sender ID
When an SMS is sent to a mobile subscriber, the subscriber's mobile handset displays sender details regarding the SMS. The sender information is either a mobile number or an alphanumeric text. This alphanumeric text is called Sender ID
Bulk SMS sender addresses in India should reserve the first two characters to identify the provider and region, as per TRAI regulations. Hence, the first character is the provider and the second is the region from which the message is sent. Below is a reference for you to find out where the message originated. The characters after the first two identify the name the sender has registered with this provider.