Additional Details ------------------------------ Product description: The Direct Inward Dialing Trunk cartridge routes calls from the public network directly to Norstar station sets, bypassing an attendant and therefore reducing traffic to the central answering position. This card provides access for up to 4 central office lines. This trunk cartridge is compatible with the Modular 8x24 (Release DR4 or higher) and the Modular ICS and supports disconnect supervision, but does not support CMS/CLASS services. It may be inserted into either the Copper Trunk Module or the Fiber Trunk Module.