1- and 3-month follow up (after the random allocation) will be conducted by a trained interviewer (blinded to the group assignment) via telephone interview. Subjects who have reported abstinence from smoking at the follow-up will undergo a non-biochemical validation to validate their quitting status. They will be enquired a few questions about their quitting experience and impression, and their family members will be invited to report the smokers' smoking and quitting status thru telephone interview. Also, they will be invited by the interviewer to have biochemical validation tests (saliva cotinine test and exhaled CO test).