Sender ID is a set of characters that represents the identity of a sender. A sender ID can have numbers, alphabets or can even be alphanumeric. It is used to identify who is sending the message to recipient.
A Sender ID SMS can have short codes or long codes as well. So, instead of the message coming from a mobile number which is not feasible as well as professional, you can choose your company name, campaign name or even a SC or LC. Thus by using a Sender ID, your customers will immediately recognize who the SMS text message is from.
The length varies from country to country. Like in UAE the sender ID can of 11 character alphanumeric for transactional while 8 for promotional with a prefix of AD-, while India has 6 characters in it. It also varies in case of promotional and transactional SMS for a few countries like Saudi Arabia.