The objective of this study is to conduct a randomized controlled trial to determine whether the use of the COach2Quit application (app) reduces smoking more than brief advice for smoking cessation. The investigators hypothesize that real time biomarker feedback and messaging support from the COach2Quit app will lead to greater smoking cessation rates than brief anti-smoking advice alone. If effective, the COach2Quit app could be an easily accessible and cost-effective tool to help smokers quit. The findings from this trial could have implications for the delivery of future outpatient smoking cessation programs.