Assertion: phone system's line | /r/AtLocation | line units
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Source sentences:
text: In contrast to Nortel's DMS-100 which uses individual line cards with a codec, most lines are on two-stage analog space-division concentrators or Line Units, which connect as many as 512 lines, as needed, to the 8 Channel cards that each contain 8 codecs, and to high-level service circuits for ringing and testing.