US phone number, optional +1 prefix and parentheses, then 3-3-4 digits. A lookbehind anchors before a leading + or (, which \b would miss, and a lookahead stops a trailing digit run. The area-code parentheses are paired, so a number written inside parentheses does not swallow the opening one.
Label: US_PHONE
(?<![\w+])(?:\+?1[\s.-]?)?(?:\([2-9]\d{2}\)|[2-9]\d{2})[\s.-]?\d{3}[\s.-]?\d{4}(?!\d)Call +1 (415) 555-0123 before noon. → +1 (415) 555-0123Office: 415-555-0123 → 415-555-0123Cell (415) 555-0123 → (415) 555-0123Call 115-555-0123 now555-0123Tags: us, contact