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The same ten-digit LRN can be used for every ported number served from the switch to which the LRN's NPA-NXX is assigned. The LRN is not a telephone number. The same ten-digit string could be used both for an LRN and for an individual telephone number assigned to the LRN's switch. However, the best practice is to avoid using the same ten-digit string for both a consumer's telephone number and an LRN. Local Number Portability (LNP) relies on the location routing number.
There are currently over 500 million LRNs.