Proliferation of data services has made it mandatory for operators to be able identify geographical regions with 3G connectivity discontinuity in a scalable and cost-efficient manner. The currently used methods for such analysis are either costly -such as in drive tests, partly unreliable -such as in network simulation approaches, or are not precise enough-such as in base station key performance indicators (KPI) based approaches. In this paper, towards addressing these inadequacies, we propose a 3G coverage analysis method that makes use of "big data" processing schemes and the vast amounts of network data logged in mobile operators. In the proposed scheme, the BSSAP mobility and radio resource management messages between the BSS and MSC nodes of the operator network are processed to identify inter-technology handovers from 3G (WCDMA) access to 2G (EDGE, GPRS, GSM). Demonstrative examples show that the proposed mechanism produces accurate and precise results, outperforming the base station KPI-based approach.