CSV phone number normalizer
Upload a CSV, pick the phone columns, and every number is rewritten in one format. Invalid numbers are flagged in a new column, everything else is left alone. Runs in your browser; nothing is uploaded.
Comma or tab separated. Up to 50,000 rows. The file never leaves your browser.
Why normalize the phone column before an import
Lead sources each write numbers their own way: (415) 555-2671 from a web form, 1-415-555-2671 from a purchased list, 415.555.2671 x12 from a trade show scanner. Many dialers, SMS tools and CRMs reject or mis-dial anything that is not in the format they expect, and duplicate checks miss the same number written two ways.
Rewriting the column to a single format, usually E.164, before the import fixes both problems and shows you which values were never phone numbers at all.
What formatting can't tell you
A clean format says nothing about whether the line is in service or what kind of line it is. Dead numbers, landlines and VoIP lines only show up with a live carrier lookup.
Upload a CSV. Get back every number marked valid or dead, mobile, landline or VoIP, with carrier.
Start 7-day free trial →Just have a plain list of numbers? Use the bulk phone number formatter. Remove repeat leads with the duplicate lead remover, or read the phone list cleaning guide.
Questions
What does it change in my CSV?
Only the phone columns you select. Each number is rewritten in the format you pick, or written to a new column next to it if you choose "Add a new column". Every other column and every row stays exactly as it was, plus one phone_format_issue column that explains any number that could not be normalized.
Which format should I pick?
E.164 (+14155552671) is the international standard and the format most dialers, SMS platforms and CRMs expect on import. Pick a US display format like (415) 555-2671 only if the tool you are importing into asks for it. Non-US numbers always stay in E.164.
What counts as an invalid number?
A value that cannot be a real number by its structure: too few or too many digits, an area code or exchange starting with 0 or 1, a service code like 411 used as an area code, or the 555-01XX range reserved for fiction. Extensions such as x12 are removed.
Is my file uploaded anywhere?
No. The file is read and processed in your browser. Nothing is sent to TrueSearch or anyone else, and nothing is stored after you close the page.
Does a normalized number mean it works?
No. This tool checks format only. A perfectly formatted number can still be disconnected, a landline that cannot receive texts, or a VoIP line. Finding that out needs a live carrier lookup, which is what TrueSearch for Business does.
This guide is general information, not legal advice. TrueSearch for Business checks validity, line type and carrier from licensed telecom data. It does not check the National Do Not Call Registry, state DNC lists or the FCC Reassigned Numbers Database. Not a consumer reporting agency; not for FCRA purposes.