Transcribing long repeating phone numbers

Solution 1:

Say the numbers grouped as they are written. In the UK, it's more usual (in my experience) to use treble instead of triple, but it's all quite idiosyncratic.

Three-digit numbers are generally read out individually unless there is a trebled number or the second pair is doubled.

Groups of four numbers are generally read out individually unless there are groups.

Examples. Do not attempt to call these numbers.
184-555-5555: one eight four, treble five, double five, double five
118-500: one one eight five hundred
118-118: one one eight one one eight
118-177: one one eight one double seven
999: nine nine nine
112: one one two
01684-566778: oh one six eight four, five double six, double seven eight

In the UK, it's not usual to say things like fifty-five in telephone numbers:

01684-556677: oh one six eight four, double five, double six, double seven
not fifty-five, sixty-six, seventy-seven

Reading grouped digits as numbers like that is a continental thing: the French and Germans do it as their phone numbers are customarily represented in two-digit groups.

Solution 2:

Since the numbers in phone numbers are grouped, it's more clear to the listener if you say them in the same groups with an optional pause between the last pairs of digits. Thus I would suggest:

one eight four, five five five, five five five five
one eight four, five five five, five five, five five
one eight four, five five five, fifty-five, fifty-five

Your intonation can also help deliver the numbers so that the listener knows where you are in the phone number.

Solution 3:

If my number was 555-5555, I think I would enunciate it like this:

Five-five-five. [pause] Fifty-five fifty-five.

This isn't necessarily widely practiced, and it's certainly not prescribed, but it seems like a practical approach to eliminating or reducing miscommunication.

As an aside, contrary to what Andrew Leach has said about the UK, in the US, grouping consecutive digits of a phone number into a "paired" two-digit number is not at all uncommon, particularly when referring to one half or the other of the last four digits. For example: