Ellular Phone Etiquite while used for business

from the book Complete Office Handbook third edition, by Susan Jaderstrom, page 544,the use of cell phone work related, no fluff, no use of I ,so,me.thereafter,therefore, (This is a final Exam) must be perfect grammer,puntutions,and spelling, has to be perfect . please, tell what I learned on this topic in capter 21 page 544 ccellular phone etiquite of this book.