Background:
Thailand National Quitline (TNQ) provides reactive and proactive counseling without nicotine replacement therapy as well as information to callers to help persons quit smoking. TNQ began providing service on 2009. Since 2011, the TNQ call system and data-base system have been continuously developed for service improvement. TNQ's created an interventions delivered via text messaging (short message service, SMS) may increase access to the services that promote smoking cessation across diverse populations.

Methods:
This quasi-experimental study aims to study the effect of SMS to Quit on quit attempt, quit rate over 7 days and 1 months, and satisfaction among smokers who called the Thailand National Quitline (TNQ) between September 2016 to February 2017. A sample of 650 smokers was voluntary recruited. Data were collected from TNQ's database and telephone interviewing throughout September 2016 to June 2017. Research instruments included 1) demographic data and smoking screening, 2) the Quit Smoking Questionnaire, and 3) the Satisfaction Questionnaire. From 650 participants, there were 386, 143, and 121 smokers who received both SMS to quit and telephone counseling, SMS to quit, and counseling, respectively. The majority of participants (85.85%) were males. Almost fifty percent of the participants were aged between 25 and 44 years. The average cigarette used per day was 14 cigarettes (SD= 6.72) and average duration smoked was 9.23 years (SD= 1.67). Data were analyzed with descriptive statistics and logistic regression.

Results:
The participants who received SMS had stop smoking for at least 24 hours (quit attempt) and continuous abstinence rates over 1 month statistically significant higher than those who received telephone counseling and both SMS and counseling (p< .05). A difference in significance did not show on analysis of caller's satisfaction with those in three groups.

Conclusions:
SMS to quit was effective for helping smokers were able to change their behaviors.