In this paper, the Sθ (Δ) and Nθ (Δ) summabilities are used along with the notion of weakly unconditionally Cauchy series (in brief wuC series) to characterize a Banach space. We examine these two kinds of summabilities which are regular methods and we recall some features. Furthermore, we investigate the spaces SNθ ( Σ pΔwp) and SSθ ( Σ pΔwp) which will be thought to characterize the completeness of a space.