Aims Screening services for early detection of patients is one of the important capabilities of the health system with a proper referral system. In the crisis of respiratory infection of Covid-19, screening based on symptoms is one of the key measures. The aim of the current study was to evaluate the telephone-based screening and triage services in the promoted primary healthcare system with regard to the Covid-19 outbreak, in terms of reducing unnecessary referrals to the hospital. Methods This is a descriptive cross-sectional study conducted in two stages on 1,406,635 households during March/April 2020 in Ardabil province for screening and early detection of Covid-19 disease. In the first stage, conducted by trained healthcare providers through telephone, individuals suspected of Covid-19 were identified. In the second stage, the individuals were referred to the second level of service in comprehensive healthcare centers (16- or 24-h centers) for clinical evaluation by a physician. Results The results showed that before establishing a screening and triage system for patients in comprehensive healthcare centers, all patients were referred directly to the hospital, while after the implementation of the program, a significant reduction in hospital visits was observed and a large number of patients undertook the care and triage services in comprehensive healthcare centers. Conclusion The use of a grading system in referring patients with suspected cases, triage of patients according to symptoms at the comprehensive health centers, and activation of home isolation were the most important factors in reducing the burden of unnecessary referrals of patients to the hospital.