arXiv:2609.26136v2 Announce Type: replace Abstract: This paper discusses key challenges and opportunities associated with deploying distributed acoustic sensing (DAS) over existing optical telecommunication networks. We review recent approaches to DAS interrogation and their compatibility with data transmission over deployed fibers, and present complementary investigations addressing three challenges: the influence of fiber-to-environment mechanical coupling, the single-shot extraction of distributed birefringence information using polarization-diversity DAS, and the impact of laser phase noise on continuous-wave phase-encoded DAS. These investigations rely on different forms of evidence: field measurements on a deployed telecommunication cable, laboratory experiments using fiber spools, and numerical simulations, respectively. The results illustrate complementary aspects of DAS deployment, from the interpretation of measured strain to polarization-sensitive sensing and phase-noise mitigation. They also highlight the need for further validation and integration of these approaches under operational telecommunication-network conditions.