e also key differences resulting from their particular history and evolutionary path and from particulars of the market which they address. At industry conferences and trade shows, OSS vendors are repeatedly told that no two telcos are alike and successful OSS vendors have taken this message to heart, ensuring that their offering is not inadvertently designed in such a way that would serve to lock a telco into some particular business process design. In the past, the biggest competitors of OSS vendors have been in-house development teams of tel- cos themselves. A carrier or service provider knows its own needs better than any- one else knows them, and often has the resources to build its own OSS from the ground up. In the not-too-distant past, all carriers wrote their own OSS software. Now, the benefits of buying from independent and specialist OSS vendors are unde- niable and widely known, SO that carriers and service providers are increasingly 26 The same is happening in the network equipment space. For example, Wipro says in "Packet over SONET interface: a design strategy", a December 2001 whitepaper: "There is a definite shift in product engineering today, away from 'developing everything in house'. Network equipment vendors are increas- ingly looking out for components, so that they could concentrate on fine-tuning system architecture." 6 Service Provisioning and Activation choosing to shun in-house development. 26 However, the background of being able to write an OSS precisely how they want it written remains a high-order issue for carriers, even as they become customers of OSS vendors. Indeed, customisation - including the rewriting of large slabs of code - is something with which OSS ven- dors, unfortunately, are very familiar. This operates as a powerful incentive to OSS vendors to build generality, programmability and well-defined interfaces into their OSS software offering so that it can be implemented in unique environments with minimal hard coding and, as far as possible, avoiding long and complex im