Bellcore has developed a model to support the periodic calculation and reporting of customer costs resulting from poor quality in telecommunications switching system software. This model is designed to provide, as a primary output, total switching system software cost of poor quality, along with a breakdown of this total by major cost component. The primary input to the model is software RQMS data, described in Bellcore's reliability and qualify measurements for telecommunications systems, TR-TSY-000929, and reported by switching system suppliers to the divested Bell operating companies (telcos) on systems operated by these companies. Telco and switching system supplier alike are expected to benefit from the ongoing application of the model, through which accumulated maintenance cost information will be made available to support telco switching system management functions and supplier quality improvement efforts.>

Reliability of software used in telecommunications networks is a crucial determinant of network performance. Software reliability (SR) estimation is an important element of a network product's reliability management. In particular, SR estimation can guide the product's system testing process and releasability decisions. SR estimation is performed using an appropriate SR estimation model. However, the art of SR estimation is still evolving. There are many available SR estimation models to select from, with different models being appropriate for different applications. Although there is no "ultimate" and "universal" SR model on the horizon (and there may not be one in the foreseeable future), methods have been developed for selecting a trustworthy SR model for each application. The present authors have been analyzing and adapting these methods for applicability to network software. Their results indicate that there already exist methods for SR model selection which are practical to use for telecommunications software. If utilized, these methods can promote significant improvements in SR management. The paper presents the results to date.>