Phone columns often hide duplicates because the same number is written as `(555) 010-2000`, `555.010.2000`, and `555 010 2000`. The contact is the same, but the sheet does not read that way.
Phone formatting gets messy faster than most fields. Once a file has been exported, merged, and re-saved a few times, the same number can appear in several visual formats.
The goal is not to invent a perfect global phone format. It is to strip obvious formatting noise so the column becomes easier to search, compare, and dedupe.
When phone values are inconsistent, the sheet looks larger and messier than it really is. Standardizing them makes review easier and helps expose contacts that only looked different because of formatting.
Do this before CRM import, before running outreach from a spreadsheet, and before trying to identify duplicates in a merged contact file.
Open the cleaner, check the before and after view, and export one cleaned CSV you can actually use.