Semiconductor quantum dots (QDs) so far have exhibited exceptional performance as key elements, i.e., quantum light sources and spin-photon interfaces, for quantum repeaters, but only in the near-infrared (NIR) regime. This review presents the physics and the technological developments towards epitaxial QD devices emitting at the telecom O- and C-bands for quantum networks. The paper also discusses the challenges and opportunities to realise future telecom QD devices with improved performance and expanded functionalities by taking advantage of hybrid integration.