Cisco Third-Generation Multiflex Trunk Voice/WAN Interface Card - Expansion module - EHWIC - T1/E1 x 1 - T-1/E-1 - for Cisco 1921, 1921 4-pair, 1921 ADSL2+, 1921 T1, 1941, 2901, 2911, 2921, 2951, 3925, 3945