What is the ITU E.164 Standard?
E.164 is the international telecommunication numbering plan that ensures every phone on the planet has a globally unique address. An E.164 number begins with a leading plus sign (`+`), followed by the country code (1 to 3 digits), subscriber national destination code, and subscriber number, containing a maximum of 15 digits with zero spaces, dashes, or parentheses (e.g., `+14155552671`).
Client-Side Regular Expression Normalization
Cleaning phone numbers involves three algorithmic steps: stripping all non-digit characters (`/[^0-9+]/g`), resolving national trunk prefixes (e.g., converting leading UK `07` into `+447`), and prepending the international country calling code.
Pasting customer contact lists into random web formatters violates GDPR and CCPA. DocSwift normalizes CSV databases entirely in local browser memory with zero server uploads.
Step-by-Step Tutorial
Strip Formatting Punctuation
Remove spaces, parentheses, dashes, and periods using client-side regular expressions.
Apply Country Calling Code
Detect or apply default international country prefixes (e.g., +1 for US/CA, +44 for UK).
Export Normalized Contact List
Save the cleaned CSV list ready for instant Twilio, WhatsApp Business, or CRM ingestion.
Ready to Try It Yourself?
DocSwift processes everything directly on your device. Fast, safe, and completely free forever.
How helpful was this guide?
Rated 4.9 / 5 by 3,420+ users worldwide
Share with Colleagues & Friends
Help others protect their document privacy
Frequently Asked Questions
What is the maximum character length of an E.164 phone number?
E.164 permits a maximum of 15 digits (excluding the initial plus sign).
Are my customer phone records uploaded to DocSwift servers?
No. String regex processing and CSV formatting run 100% locally in your web browser. Your customer data never leaves your machine.