Receiving smoking cessation services from telephone quitlines significantly increases quit success compared with no intervention or other quitting methods. To affect population-level smoking, quitlines must provide a sufficient proportion of smokers with effective interventions. Nationally, quitlines reach around 1% of adult smokers annually. From 2011 through 2016, the average annual reach of the New York State Smokers' Quitline (NYSSQL) was 2.9%. We used data on the reach and cessation outcomes of NYSSQL to estimate its current impact on population-level smoking prevalence and to estimate how much reach would have to increase to achieve population-level smoking prevalence reductions. We estimate NYSSQL is associated with a 0.02 to 0.04 percentage point reduction in smoking prevalence in New York annually. If NYSSQL achieved the recommended annual reach of 8% (CDC Best Practices) and 16% (NAQC), state-level prevalence would decrease by an estimated 0.07-0.12 and 0.13-0.24 percentage points per year, respectively. To achieve those recommended levels of reach, NYSSQL would need to provide services to approximately 3.5 to 6.9 times more smokers annually. Given their reach, quitlines are limited in their ability to affect population-level smoking. Increasing quitline reach may not be feasible and would likely be cost-prohibitive. It may be necessary to re-think the role of quitlines in tobacco control efforts. In New York, the quitline is being integrated into larger efforts to promote cessation through health systems change.