Evidence-based treatments (e.g. quitlines) are greatly underutilized by smokers limiting their public health impact. A three-session phone intervention for nonsmoking family members and friends (i.e. support persons) was successful for increasing smoker quitline enrollment. To enhance the intervention's potential translatability, in this study, we delivered treatment for the non-smoker within ongoing quitline services and compared the efficacy of the three-call intervention to a streamlined version (one call). A total of 704 adult non-smokers (85% female, 95% White) wanting to help a smoker quit and recruited statewide in Minnesota participated in this randomized controlled trial with parallel groups. Non-smokers received mailed written materials and were randomly assigned to a control condition (no additional treatment, n = 235), or to a one- (n = 233) or three-call (n = 236) intervention delivered by quitline coaches. The main outcome was smoker quitline enrollment through 7-month follow-up. Smoker quitline enrollment was similar for those linked to non-smokers in the one- and three-call interventions (14.6% [34/233] and 14.8% [35/236]), and higher than for smokers linked to control participants (6.4% [15/235]), P = 0.006. Just one quitline coaching call delivered to non-smokers increased treatment enrollment among smokers. The reach of quitlines could be enhanced by targeting the social support network of smokers.