 4-port OC3/STM1 or 1-port OC12/STM4 or 4-port T3/DS3 ATM Line Module: supports (4) OC3/STM1 ATM or (1) OC12/STM4 ATM or (4) T3/DS3 ATM interface(s) with 256MB of memory. Requires an OC3/STM1, OC12/STM4, or T3/DS3 IOA. Supports 1:1, 2:1, 3:1, 4:1, and 5:1 - Certified Pre-Owned |