HWIC-4B-S/T=

Cisco High-Speed 4-Port ISDN BRI S/T – Voice / fax module – HWIC – ISDN BRI ST – digital ports: 4 – for Cisco 1841, 1841 3G, 1841 ADSL2, 1921 4-pair, 1921 ADSL2+, 19XX, 28XX, 29XX, 38XX, 39XX