ing engineering effort. Neither all-IP nor other approaches has succeeded in this at the network layer due to various reasons, such as technical problems with roaming, unwillingness of CSPs to cut the balance sheet value of their investments to old network technology and uncertainty of new business models replacing lost revenue on voice communication with added value services, advertisements and other new sources. All these changes related to all-IP adoption will have a major impact on OSS/ BSS software. Billing systems accounting for half of the OSS/BSS product revenue will become less necessary if monthly flat fees are commonly adopted. OSS/BSS software for customer identity management relying on phone number or SIM card identity will have to be revised, etc. If advertisements were to become the major income for consumer communication service providers, the operator segment might evolve towards the dual model of i) bit-pipe operators servicing enterprise, custo- mers and advertisement agencies funding the monthly fees of consumers, and ii) specialized value added service operators providing service packages or individual services for the packagers. In addition, network equipment vendors might contrib- ute to the first category by providing capacity in a form of managed services. In most of these scenarios the number of OSS/BSS software vendors providing software related to the network layer is likely to decrease along with the decreased number of network equipment vendors. As the analysis of mergers and acquisitions shows, the number of software vendors seems to be decreasing although the vertical software market has not matured yet. As a general implication, the industry evolution life cycle and the vertical software market evolution seem to be only loosely coupled and the lack of software market growth causes market consolida- tion even in the middle of the vertical market evolution. However, the number of software vendors with products related to customer interaction is more difficult to predict as the borde