No brackets around area codes. So it’s 01234 567890 not (01234) 567890.
And use spaces instead of hyphen between numbers so it’s: 07977 123456 in the UK and 555 555 5555 in the US.
You’re not alone if these trip you up.
We're not a fussy bunch, but just so you know...
No space between the number and the measure such as 10kg, 800g, 9lbs, 7oz.