al- lenges CSPs seem to face with this approach come from the decreasing value of prior investment on old technologies, from the migration costs as well as from uncertainty of new business models. As billing basic voice communication becomes impossible, the revenue should come from monthly fees, 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 a 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 communica- tion service providers, the operator segment might evolve towards the dual model of (1) bit-pipe operators servicing both enterprise customers and advertisement agencies subsidizing the monthly fees of consumers, and (2) specialized value added service operators providing service packages or individual services for the packagers. Yet another possible future for CSPs is that they specialize more and more on developing new value added services for customers. In this scenario the operators still own networks, although they have outsourced network operations to third parties, either to global IT integrators using their internal OSS/BSS software, or to network equipment vendors with their proprietary OSS/BSS systems. Later on, CSP operations outsourcing may evolve into white-label bit-pipe operators servicing multiple CSPs with their gradually extending networks. 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. This might be the case even if the introduc- tion of new network technologies still remained active. As the analysis of mergers and acquisitions show, the number of software vendors seems to b