Annotation: Telecommunications laboratory (telco lab) is the next step in the old hardware collection’s further usage and analysis. About 10+ various [mainly U.S.Robotics (USR) branded] voice 56kbit (fax)modems for dial-up Internet connection had been collected. This article gives a Prove of Concept (PoC) to the modem-modem link establishment over the VoIP RTP stream with aim to build a dial-in ISP service. Various VoIP technology’s underlying parameters, and modem configurations had been tuned with batch dial-up connection testing being executed, and then commented....