Photonic and electronic integration technology is pushed forward strongly by the telecommunication market to reduce the size and the costs of each component. Electro-optical terahertz (THz) technology based on the communication wavelength of 1.55 μm can directly benefit from the development of these integration techniques. Thus, continuous wave (cw) THz spectroscopy systems bear great potential to become a highly flexible, robust and also cost-efficient tool for spectroscopy and testing. Here, we present promising concepts of telecom-based photonic integration and their impact on total system cost. The potential for cost reduction will pave the way for cw THz technology to enter the market rapidly.