This community is located on Cape Cod (Massachusetts). Like many other towns on the Cape, many were served by the Southern Massachusetts Telephone Company. Eventually their exchanges were purchased by New England Telephone...one-by-one. I do not know if So. Mass. Tel. Co. was still serving Dennisport when this image was taken. However the crossarms you see are attached via two diagional lag screws...a practice that pretty much was superceded by the single through-bolt method by around 1900. So maybe these lines had So. Mass. Tel. Co. insulators upon them?