1.5μm wavelength region is the window of optical communication. Absolute frequency references that satisfy ITU-T standards in 1.5 μm region for frequency calibration are widely needed in DWDM system. In this paper, an approach of obtaining precise frequency points which ITU-T has produced has been experimented, using an acoustic frequency shift, by calibrating Fabry-Perot etalon using double acetylene absorption lines. In the experiment, mode 1955 of F-P etalon is offset frequency-locked to acetylene absorption line P14, 195500.4023GHz, with frequency stability 108 for a 30-minute measurement. After calibrating, a series of spaced 100GHz artificial absolute frequency references in 1.5μm region are obtained.