Sis: The software installation program that was not on the Nokia smartphone in the third edition in the early days, only a small part of sis can run on the third edition, which is why many downloaded sis can't be used on our mobile phone in the third edition. With the popularity of SIXX, sis will gradually disappear from the third edition of mobile phones. SIXX: a program specially developed for the third edition, which can't be run on mobile phones that are not the third edition system. SIXX is a signed Symbian software. Sis is unsigned Symbian software or the first and second versions of Symbian software. SIS is a software technology, and the three-in-one platform security isolation technology perfectly combines security, intelligence and speed.