A framework for simulating wide area measurement system (WAMS) of electrical transmission networks to test measurement algorithms is proposed in the paper. The framework has been implemented by a joint team involving the Italian transmission system operator (TSO), Terna S.p.A, and the University of Naples Federico II, and is essential to assess the performance of algorithms estimating network variables before making them operational on the real WAMS. On the other hand, the algorithm performance must be evaluated on a system that reproduces as faithfully as possible the problems characterizing an actual monitoring system. The authors propose a mixed solution including open-source software for managing timestamped data streams and Matlab script for both emulating PMUs and measurement algorithm. In the paper also preliminary tests carried out in order to assess the framework reliability are described.