The four-port adapter (PA-4T+) provides four synchronous serial ports. Each port supports full-duplex operations at T1 and E1 speeds. A single port can support up to E2 speeds. Each port also supports a variety of interface types, determined by the separately purchased cable type connected to it. Supported interfaces include EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA-530, allowing flexible deployments as either DCE or DTE equipment. The four-port adapter is the most cost-effective solution for low-traffic WAN connections or remote Cisco 7200 installations. The PA-4T+ is supported on the Cisco 7200, C7301, C7304, C7500 and C7600. The PA-4T+ port adapter requires only a single slot in a Cisco 7200 Series and 7301 routers. For the Cisco 7304, it requires the port adapter carrier card option. For Cisco 7500 Series routers, it requires one of the two available adapter slots on a Versatile Interface Processor (VIP2) and an Enhanced FlexWan on the Cisco 7600.