The WIC-2T provides two serial ports using the Smart Serial connector. Asynchronous support with a maximum speed (per port) of 115.2 Kbps, minimum 600 bps. If you need to run at speeds lower than 600 bps, use the AUX port instead. Synchronous support with a maximum speed of 8 Mbps per port. Supports one port at 8 Mbps when used in NM-1FE1R2W, NM-1FE2W, NM-2FE2W, or NM-2W, or Cisco 2600 chassis WIC slots. All other WIC ports on that network module or Cisco 2600 chassis must not be used. Supports two ports at 4 Mbps each when used in NM-1FE1R2W, NM-1FE2W, NM-2FE2W, or NM-2W, or Cisco 2600 chassis WIC slots. All other WIC ports on that network module or Cisco 2600 chassis must not be used. Supports 8 Mbps on all ports simultaneously on 2691, 3725, and 3745. No restrictions. Maximum six ports at 8 Mbps each. address:yueshan6666(at)yahoo.com.cn