It would almost be a valid Wokingham (Berkshire UK) number (well 0118 999 8819 would be) except I think after the second 9 there's no allocated numbers.
That is, it's not possible to dial in the UK, you would get an number unobtainable tone as soon as you dial 0118 99 on a landline phone.
Not really. Some people do, but if you look at printed numbers it's usually a space. At least from my experience.
Number formatting is a funny thing too. So Wokingham (which is on the Reading 0118 prefix) is 0118 9. But the format is generally written 0118 9xx xxxx and not 01189 xxx xxx. But other area codes are like 01268 xxx xxx. London is especially interesting because people format differently, mostly based on age. See London numbers used to be 01 xxx xxxx. So people wrote their numbers as (01) xxx xxxx (if you lived in London you just dialled the last 7 digits). But over time the London prefixes evolved many times. Now it is 020 for London and xxxx xxxx. But the main first digits often still follow older patters of 7 for inner London and 8 for outer London (for older numbers at least). So older people (and I mean my age, not elderly) often format their number as 0208 xxx xxxx.
Went off on a tangent a bit there. Main story is, in my experience no hyphens is more common. But people do sometimes use them.
I'm okay with tangents because I love learning about formatting & cultural differences. I think it's fascinating!
And yeah that's interesting because here in the US, putting a hyphen in between each section is typically much more common. For example, we'd write 123-456-7890.
How do you prevent overflow with line breaks without having to use every single time, though? With a visible separator, there'd be no need for that.
No hyphens follow some international standards such as those of the ITU. ITU E.123 recommends: 'only spaces be used to visually separate groups of numbers "unless an agreed upon explicit symbol (e.g. hyphen) is necessary for procedural purposes" in national notation'