There is no universal technique in statistical mechanics to analytically solve the problem of dissimilar adjacent coupled phase oscillators in a ring at the switch to synchrony. The solution to the four oscillators′ case presents a first step to constructing a regular method based on unscrambling the sync dynamics of a few oscillators. The local interaction between the adjacent oscillators and the periodic boundary conditions introduce finer points to the synchronicity. We notice that the synchronized state has different noticeable characteristics depending on the arrangements of the primary frequencies. This, in turn, yields an involvedness in obtaining an analytic solution. To overcome the difficulty, we classify the twenty-four possible arrangements for the four local coupled phase oscillators in a ring into three classes. Consequently, we introduce a method to rearrange the initial frequencies into consecutive pairs of nearest-neighbor elements for all three classes. Thus, we can define the effective parameters (in terms of the sequential couples of adjacent oscillators) that rule the solution for the oscillators in a ring. Furthermore, the unison behavior resulting from coupling emerges when a clearly defined phase lock condition develops. We utilize the phase condition and trigonometric identities to find a soluble-effortless relation. Consequently, we derive an analytic expression that predicts the threshold coupling for each class when the oscillators synchronize. The formula for the critical factor allows us to obtain usable expressions to determine the phase differences at the transition into a sync stage. Therefore, we figure out the sync mechanism a priori, knowing the initial frequencies.