context: Tim Thomas (Will Smith), while carelessly sending a text message while driving, veers across the center line into oncoming traffic and causes a multi-car crash in which seven people die: six strangers and his fiancÃ©e, Sarah Jenson (Robinne Lee).
  Two years later, in a bid for atonement, Tim sets out to save the lives of seven good people by donating his own vital organs, a process that will be completed after his planned suicide. A year after the crash, having quit his job as an aeronautical engineer, Tim donates a lung lobe to his brother Ben (Michael Ealy), an IRS field agent. Tim then steals his brother's federal IRS identification badge and credentials, puts his picture over Ben's, identifies himself by his brother's name, and uses Ben's privileges to check out the financial backgrounds of further potential candidates for his donations. In each case he "interviews" them first to determine if they are good people.
  In one case, the director of a hospice nursing home facility, who had an unsuccessful bone marrow transplant, seeks a six-month extension on his back taxes. Tim, now going by his brother's name, is unsure of the man's ethics, because he claims to be insolvent, yet drives a new BMW. To resolve the issue, "Ben" passionately asks a resident patient, an elderly bedridden woman, to tell him whether he is a "good man", only to discover that the man is punishing the woman for refusing to take a new medication by not allowing the nurses to bathe her.
  Six months later, "Ben" donates part of his liver to a Child Protective Services social worker named Holly (Judyann Elder). He then finds George (Bill Smitrovich), a junior hockey coach and donates a kidney to him. He then donates bone marrow to a young boy named Nicholas (Quintin Kelley), opting to have no anesthesia during the procedure, an evident consequence of his desire for atonement. In each case he does not tell the people what his intentions are for his donations, despite being repeatedly asked.
  Two weeks before he dies, he contacts Holly and asks if she knows anyone "in the system" who needs and deserves help but is too proud to ask for it. Holly suggests Connie Tepos (Elpidia Carrillo), who lives with her two kids and an abusive boyfriend, but can't afford to leave. When "Ben" arrives to "interview" her under the guise of dealing with the IRS, Connie is embarrassed and humiliated that he knows what's been going on. She defends her boyfriend, is offended by "Ben"'s suggestion that she should leave with her kids, and kicks him out of her house. In the meantime, "Ben" moves out of his house and into a local motel, taking with him his pet box jellyfishâdecidedly the most venomous creature on earth, with its sting causing death in three to five minutes. That night, after being beaten by her boyfriend again, Connie contacts "Ben". He meets her, tells her not to be weak, and gives her the keys and directions to his beach house. She takes her two children and they move into the house. Then she reads a letter from "Ben" which includes the deed to the house, again giving no explanation, and asking for her to (1) respect his wishes, (2) not try to contact him, (3) not tell anyone how she got the house, and (4) "live life abundantly".
  "Ben"'s sixth candidate is Ezra Turner (Woody Harrelson), a blind telemarketer for a meat company, who plays the piano. "Ben" calls Ezra and harassed him at work weeks earlier, to see if he was quick to anger; when Ezra remains calm and humble through the abuse, "Ben" decides he is worthy.
  "Ben" then contacts Emily Posa (Rosario Dawson), a wedding announcement/greeting card printer who has a congenital heart condition and rare blood type that has left her with only weeks to live. "Ben" "interviews" her at her home, again under the guise of an IRS investigation, and more or less stalks her at the hospital. But then he starts to spend time with her, walking her Great Dane called Duke, weeding her garden, and fixing her rare Heidelberg Windmill press. He visibly fights his affections for her, again seeking atonement for the death of his fiancÃ©e, but he slowly falls in love with her.
  At one point, while comforting Emily (who's in the hospital after an emergency), he tells her the 'tale of a young boy named Tim, who wanted to fly and became a space engineer.' Emily recognizes this is an actual story of his childhood and suggested the boy was named Ben, but "Ben" corrects her by sheer reflex, telling her that the boy is called Tim... obviously himself.
  Tim's brother, the real Ben, finally tracks "Tim-Ben" down at Emily's house, saying that he must return his IRS credentials. After a passionate sexual interlude with Emily, and with Ben waiting outside her house, Tim disappears out the back door, leaving her sleeping. He returns on foot to the motel, first stopping by the hospital to ask the doctor if there is any chance that Emily will improve. Discovering that she will likely die before a donated organ becomes available, he decides "it's time".
  Tim then fills the motel bathtub with ice water to preserve his vital organs, calls 9-1-1 emergency and reports his own suicide, climbs into the tub, and releases his box jellyfish into the water with him. The jellyfish wraps its tentacles around his arm, causing a quick but excruciatingly painful death.
  At the hospital, his best childhood friend Dan (Barry Pepper) acts as executor of Tim's living will to ensure that his organs are donated to Emily and Ezra. Ezra receives Tim's corneas, which cure his blindness, and Emily receives his heart.
  Afterward, Ben finds letters from Tim that he is to give to each person explaining why he did what he did. This leaves Emily heartbroken. Emily finds Ezra (now a school teacher) at his kid's choir concert at a park and stops him as he passes by. Having never met before, Emily is fixated on Ezra's eyes, knowing they belonged to Tim. Emily begins to break down, which clues Ezra in to who she is. When he says, "You must be Emily," she breaks into tears and they share a heartfelt embrace out of mutual love and respect for Tim.
question: What is Tim doing that causes the crash?
answer: Sending a text message