As name indicates, Messages which are promotional or advertising in nature and being sent to an unknown set of people to push SMS for awareness, generating leads, sending offers etc. are known as Promotional SMS.
Or in other words, SMS related to product, Service or Brand having promotional contents are said to be promotional.
Few Cases are listed below-
1. SMS related to product discount or offer.
2. SMS related to Service discount / offer to its customers.
3. SMS containing Brand Name and being advertised to group of unknown people.