The comprehension of the dynamic and static structure of a system is of main importance for purposes of adding features, bug solving, and for redesign activities. This holds particularly for systems where the features tend to be strongly intertwined. In telephony systems, there is feature interaction both at specification and implementation level. In the present paper we report on a dedicated environment called URSA: Understanding and Recovery of the Sopho Architecture. A special role is played by an extended Message Sequence Chart language called CMSC.