ration. On one hand, this seems to be because of the vendors' active business strategies of conquering a larger share of the market (see also Frank et al. 2007). On the other hand, this development arises from the customers' (the CSPs') aim to concentrate their procurement to only a few software vendors each. Thus, in this stage, the number of firms should decrease. The theories and indicators related to the described stages are summarized in Table 1. According to the industry lifecycle theory, the number of firms competing within an industry increases in the growth stage and declines in the maturity stage. Conversely, the concentration of the industry, measured with the HHI index, decreases in the growth phase and later, in the maturity stage, raises again. With regards to measuring the extent of vertical integration, we suggest examination of different software vendor strategies, namely their breath of operations (cf. Frank et al. 2007). In the growth phase, the industry has more specialized niche companies, Table 1 Stages and indicators of the OSS/BSS software industry evolution Stage Early Growth Maturity Theory (indicator) Industry lifecycle(number of firms) Vertical integration(breadth of operations) Consolidation(HHI index) L. Frank et al. whereas in the maturity stage there should be more companies providing software for the entire vertical process area or broadly for multiple segments. The market data provided by Dittberner Inc. enables us to investigate the evolution of the mentioned indicators from the years 2000 to 2006. The OSS industry was growing rapidly during the mid-1990, and we assume the industry to have passed the first stage. Thus we hypothesize the industry having started from the second stage (growth) and shifted to the third stage (maturity) within the observed time frame. For this shift between stages two and three, the following hypotheses can be derived from Table 1: 1. The number of firms decreases as the industry reaches the mature phase of the industry lifecycle. 2. The breadth of o