Answer
$10,000$
Work Step by Step
See page 690, The Fundamental Counting Principle:
The number of ways in which a series of successive things can occur is found by multiplying the number of ways in which each thing can occur.
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Each of the first three digits can be chosen in only one way.
Ways of choosing the
4th digit ... 10 (any of the digits 0 - 9),
5th digit ... 10,
6th digit ... 10,
7th digit ... 10.
Total codes possible (applying the Principle):
1$\times$1$\times$1$\times$10$\times$10$\times$10$\times$10$=10,000$
(This includes the number 699-0000. There are no constraints by which we should exclude it, so 10,000 remains as the answer)
