There are many ways, especially when there are multiples of the same digit.

The basic 7 digit number is generally like this:

Read the first 3 numbers as single digits, and the last four as two double digit numbers.

525-2793 is read, "Five two five, twenty-seven ninety-three."

A single zero is read as letter O.

525-2703 is read, "Five two five, twenty-seven oh nine."

2 zeroes in final position make a "hundred".

525-2700 is read, "Five two five, twenty-seven hundred."

3 zeroes in final position make a "thousand".

525-5000 is read, "Five two five, five thousand."

888-5555 could be read,"Eight eight eight, fifty-five fifty-five." or "Triple eight, fifty-five fifty-five."

In noisy conditions it's best to resort to reading each digit separately. And, this last method is correct in every case, noisy or not.

929-4501 "Nine, two, nine, four, five, zero, one."