What is the character length of sender id ?

As per TRAI regulation, the sender ID length is 6 characters.

In Transactional SMS Service you can get 6 Characters sender ID with your Company / Business name, Product name, Website name (Like SSDWEB, WEBSMS, SSDIND).

In Promotional SMS Service, you can get 6 Characters Numerical Sender ID. That Sender ID is generated randomly by telecom operators.