Direct Dialling Inwards. Enables some digital switches to receive dialled numbers directly from the trunk interface.
Direct Dialing In - to a building so everyone has a number which is directly dial-able from the PSTN (public network). As opposed to use of a human switchboard operator (`Good morning, this is Flying Boat Mobile Communications, how may I direct your call?`) or a DTMF controlled extension access facility (as in `if you know the extension you require, please dial it now`). DDI is only feasible where the number space is large; one of the reasons for dialing code changes (of which there have been several in the UK in recent years).
Digital Display Indicator
Device Driver Interface + Digital Document Interchange + Direct Dial In
DDI can be an abbreviation for: ==Companies== ==Science== ...Found on http://en.wikipedia.org/wiki/DDI
ddI and ddC:see AZT.Found on http://www.infoplease.com/ce6/sci/A0912418.html
Direct Dial InwardFound on https://www.encyclo.co.uk/local/21417
Direct Dialling In (DDI) is the provision of a block of telephone numbers for receiving calls into a company's private branch exchange (PBX) system. Using DDI, a company can offer its customers individual phone numbers for each employee or company workstation without requiring a physical line into the PBX for each connection.
Found on http://www.encyclo.co.uk/local/20632
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