It might not have a specific cultivar name if it's seed grown from a strain.

Without foliage this could be a number of different species, and the 2 species that have the most cultivars are paniculata and drummondii. There's a very similar looking Phlox that's in the Early Start Series which are intraspecific hybrids that were bred in Holland.

Why not ask the flower farmer? They would likely know exactly what varieties they're growing.

From the picture this Phlox appears to be part of a bouquet. So I'd assume it is unlikely to be P. drummondii, which is not much used in floristry.

They do not recall the name