Initial standardization efforts involved in the provision of the ONA plans by the carriers related primarily to the nature of the services offered, and not to the interactions between the different services or the nature of such interactions. This is because, in the large majority of cases, the services that were to become the Basic Service Elements were already in existence prior to the ONA mandate, and as such so were the communications protocols used between the service elements. The ONA mandate does not address how Basic Service Elements should interact, merely that they should be available on an individual basis to the ESPs and be nondiscriminatory.
Greater network access is changing the telecommunications industry to one where many third party service providers are building products that must work with products from other companies [11], [12], [10]. ONA increases the potential for vulnerabilities associated with feature interaction problems. As more services are added to the network, the potential for undesirable feature interactions will increase. Feature interaction could disrupt a needed service or be targeted for intentional abuse by computer intruders.