The plus sign disappeared from my phone numbers

International phone numbers have lost their leading plus. Some cells show an error instead, and some have collapsed into a single run of digits with the spaces gone.

Why this happens

• A leading plus starts a formula. Excel reads +44 20 7946 0018 as an instruction to calculate something, not as a label, which is why the result is either an error or a number with the plus stripped off.
• Underneath that is the same category mistake that ruins SKUs: a phone number is made of digits and is not a quantity. Nobody adds two phone numbers together, the leading zero in an area code is meaningful, and the spaces are part of how it is read.
• Long numbers then hit the precision limit as well. Once a phone number is being treated as a number at all, anything past fifteen significant digits is replaced with zeros, which is enough to damage a number written with its country code and no separators.

What to do right now

• Import the column as text rather than opening the file directly, so the plus is never read as an operator.
• If the file is already damaged, go back to the original. A stripped country code cannot be inferred from the remaining digits, because the same national number exists in several countries.
• Agree one written form with the sender if you control the exchange. E.164, which is a plus followed by digits and nothing else, is the only form that survives being passed between systems without interpretation.
• Do not fix this by formatting the column. Formatting changes what you see, and the value that lost its plus is still the value that will be exported.

Stopping it on the next file

A phone field typed as text is stored as it arrived, with the plus, the spaces, and any leading zero intact, because nothing tries to evaluate it. What a typed sheet does not do is rewrite phone numbers into a canonical form: there is no phone type here, so if you need every row in E.164 that is a rule you agree with the sender rather than something the import invents. Marking the field required is what catches the rows that arrived without one at all.

The contact list template is a sheet with those rules already set, if you want to see the shape of one before building your own.