The Cisco T1/E1 HWIC combines T1 and E1 connectivity in the same card, providing fractional or full T1/E1 WAN connectivity. The flexible WAN connectivity options, together with integrated routing, security, and voice capabilities, make the Cisco 1861 Integrated Services Router able to meet the diverse needs of enterprise-class branch offices, commercial offices, and SMB offices. The Cisco T1/E1 HWIC can be used in T1 or E1 networks, selectable by software configuration. The integrated Channel Service Unit / Data Service Unit (CSU / DSU) enables customers to consolidate Customer Premises Equipment (CPE). The Cisco T1/E1 HWIC supports balanced and unbalanced E1 connectivity.