Information technology plays an important role in telecommunication industry. Their businesses rely on some key software, such as Customer Relationship Management (CRM), charging and payment gateways. However, telecommunication companies face challenges in maintaining quality of their software. Consequently, software failures happen and these organizations cannot meet their Service Level Agreements (SLAs). It gives bad impact on customers' satisfaction and companies' performance. Therefore, this study examines factors causing the software malfunctions. The Analytic Hierarchy Process (AHP) was employed to rank these factors. To contextualize the study, a telecommunication company in Indonesia was used as a case. It was found that (1) Computational/Logic Error, (2) Insider Threat, (3) Improper Testing of Change, (4) Configuration Error, (5) Network Hardware Failure (6) Password Disclosures, (7) Denial of Services Attacks were the top rank of software failure roots.