The Cisco Clear Channel T3/E3 shared port adapter (SPA) is designed to provide direct connectivity to T3/E3 lines for full-duplex communications at the T3 rate of 44.736 MHz or E3 rate of 34.368 MHz. The ports are configurable as either all T3 or all E3. To support the widest range of operational environments and to offer the greatest flexibility in provisioning clear channel T3/E3 connections, the Cisco Clear Channel T3/E3 SPAs take a groundbreaking step and bring together proprietary subrate and scrambling features of T3/E3 DSU vendors Quick Eagle Networks (formerly Digital Link), Larscom, ADC Kentrox, Adtran, and Verilink. Subrate support in the Cisco Clear Channel T3/E3 SPAs maximizes the application of these products in service provider environments for tiered T3 services. By simultaneously supporting interoperability with a wide range of third-party DSU vendors, the Cisco Clear Channel T3/E3 SPAs offer the flexibility to support installed equipment without committing customers to a proprietary solution.