Norstar Caller ID Trunk Cartridge provides 4 LS/DS Trunks with Caller I.D. NT5B41, NT5B41GC, NT7B75AAAE, NT7B75AAAF CALL ID TRUNK CARD for MICS/CICS Nortel Norstar Phone System. Features: Capability to detect and translate incoming CMS/CLASS information from the central office for display and use on Norstar station sets Supports disconnect supervision Provides access for up to 4 central office lines System Requirements/Compatibility: Compatible with the Modular and Compact ICS Compatible with Modular 8x24 (Release DR5 or later)