Let α, β be orientation-preserving homeomorphisms of [0, ∞] onto itself, which have only two fixed points at 0 and ∞, and whose restrictions to R+ = (0, ∞) are diffeomorphisms, and let Uα, U β be the corresponding isometric shift operators on the space L p (R+) given byWe prove sufficient conditions for the right and left Fredholmness on L p (R+) of singular integral operators of the form A+P + γ + A−P − γ , where P ± γ = (I ± Sγ )/2, Sγ is a weighted Cauchy singular integral operator, A+ = k∈Z a k U k α and A− = k∈Z b k U k β are operators in the Wiener algebras of functional operators with shifts. We assume that the coefficients a k , b k for k ∈ Z and the derivatives of the shifts α ′ , β ′ are bounded continuous functions on R+ which may have slowly oscillating discontinuities at 0 and ∞.Mathematics Subject Classification (2010). 45E05, 47A53, 47G10, 47G30.