oftware on network elements. They are the primary team involved in routine trouble resolution. Tier 2 monitors the performance of the network as well as determines whether action is needed to address performance degradations. The Tier 3 organization can move between design work and operations support seamlessly. It is called in to assist on complex network problem resolution and restoration. This team also works on chronic or systemic problems and typically works with the network element vendor to do SO. The Tier 3 organization has a close partnership with the engineers who design network services and there is collaboration on the network management plan for network elements and services. Tier 3 designs and certifies the complex procedures that are required for replacing network elements, inserting new network technology, or upgrading network software. It does the technical forensics required to determine root causes of complex network outages and creates the action plans to address any gaps that are uncovered during root cause analysis. The AT&T operations organization structure also includes a Global Technology Operations Center (GTOC), a single, site-redundant network operations center shown in Figure 15.2. The GTOC manages outage escalations and provides operational oversight and coordination across the various technology-focused reliability centers, customer care, and external bodies such as the FCC. It also serves as the single communications channel to internal senior leadership SO that consis- tent and accurate information on network events reaches all stakeholders. In addition, the GTOC develops and maintains critical processes used across the entire operations organization such as the appropriate way to prepare and execute changes to the production network. The GTOC has a formidable task since AT&T's global network connects more than one billion devices in over 180 countries. There are typically over 400 network incidents each day; events that are sufficiently big to warrant GTOC engagement. There is an