What do the SP service and Unicom in the letter mean respectively?

"China Unicom" is an information subscription and on-demand service based on SMS platform, which can be used by Unicom mobile phone users. "Unicom in the letter" allows Unicom mobile phone users to enjoy life, information, business, entertainment and other information anytime and anywhere through SMS. SP(Service Provider) refers to the direct provider of mobile Internet service content application services, and is responsible for developing and providing services suitable for mobile phone users according to users' needs. SP services on the mobile phone include SMS, which is the simplest SP service, such as weather forecast, SMS magazines and so on. , including multimedia messages that users can get various personalized multimedia contents.