How does NumSwift extract phone numbers from text?

NumSwift uses advanced pattern recognition to automatically identify and extract phone numbers from any text you paste. It supports international formats and validates numbers in real-time.

Can I send WhatsApp messages without saving contacts?

Yes! NumSwift allows you to send WhatsApp messages directly to any phone number without adding it to your contacts. Just extract the number and click the WhatsApp button.

Is my data safe when using NumSwift?

Absolutely. NumSwift is completely privacy-focused - all data processing happens locally in your browser. No text or phone numbers are sent to our servers.

Does NumSwift work with international phone numbers?

Yes, NumSwift supports phone numbers from all countries and automatically detects the country format. You can also manually select your country for better accuracy.

Can I extract multiple phone numbers at once?

Yes. NumSwift can extract many phone numbers from a single text block. It automatically deduplicates results and keeps up to 50 numbers for quick access.

How do I format a phone number for international calling?

Paste the number into NumSwift and select the correct country. NumSwift validates it and shows the properly formatted international version with the correct country code.

Phone Number Formats Explained: Local, National, E.164

The same phone number can be written in half a dozen different ways. A US number might appear as:

555-123-4567
(555) 123-4567
+1 555 123 4567
15551234567
+15551234567
1 (555) 123-4567

All of these represent the same number. But depending on where you use them — a phone call, a WhatsApp message, an API, a database — only certain formats will work.

Here's what each format means and when to use which.

Local Format

The number as dialed within the same area or city. No area code, no country code.

123-4567

When it works: Calling from a landline within the same area code. Increasingly rare as mobile phones always require at least the area code.

When it doesn't work: Anywhere outside the immediate local area. Useless for digital systems, WhatsApp, or international communication.

National Format

The full number as dialed within the same country. Includes the area code (and trunk prefix, if applicable) but no country code.

(555) 123-4567       ← US national
0555 123 4567        ← UK national (0 is the trunk prefix)
030 12345678         ← Germany national

When it works: Making calls or sending SMS within the same country. Most people's default way of writing phone numbers.

When it doesn't work: International calls, WhatsApp (which needs the international format), APIs, and databases that store numbers from multiple countries.

International Format

The full number formatted for international dialing. Includes the country code and drops the trunk prefix.

+1 555 123 4567      ← US
+44 555 123 4567     ← UK (trunk prefix 0 removed)
+49 30 12345678      ← Germany (trunk prefix 0 removed)

The + sign at the beginning means "replace with your country's international dialing prefix" (00 in most of Europe, 011 in the US).

When it works: International phone calls, displaying numbers for a global audience, and as a human-readable version of E.164.

E.164 Format

The international standard for phone numbers, defined by the ITU. It's what machines use.

+15551234567
+445551234567
+493012345678

Rules:

Starts with +
Country code (1-3 digits)
Subscriber number (without trunk prefix)
No spaces, dashes, parentheses, or other formatting
Maximum 15 digits total (including country code)

When to use it:

Storing phone numbers in a database
WhatsApp wa.me links (without the +)
SMS APIs (Twilio, MessageBird, etc.)
Any system that processes phone numbers programmatically
CRMs and contact management systems

E.164 is the canonical format. Every other format can be derived from it, but converting back to E.164 from a local or national format requires knowing the country. If you need to convert numbers between formats, having the country context is essential.

How the Formats Relate

For the UK number 07911 123456:

| Format | Value | Notes | | ------------- | --------------- | ---------------------------------------- | | Local | 123456 | Just the subscriber number | | National | 07911 123456 | With trunk prefix (0) | | International | +44 7911 123456 | Trunk prefix removed, country code added | | E.164 | +447911123456 | No formatting, just digits and + |

For the US number (555) 123-4567:

| Format | Value | Notes | | ------------- | --------------- | ---------------------------------------------- | | Local | 123-4567 | Just the local number | | National | (555) 123-4567 | With area code | | International | +1 555 123 4567 | Country code added (no trunk prefix to remove) | | E.164 | +15551234567 | No formatting, just digits and + |

The Trunk Prefix Problem

The trunk prefix is the digit (usually 0) you dial before a national number for domestic calls. It's not part of the actual phone number — it's a routing instruction for the phone network.

The rule: Drop the trunk prefix when converting to international or E.164 format.

The exceptions:

US/Canada: No trunk prefix exists. The number is the same in national and international format (just add +1).
Italy: The leading 0 is part of the number and must be kept in international format.
Some countries use a different trunk prefix: Russia uses 8, some countries use other digits.

This is where most formatting mistakes happen. If you're unsure, NumSwift handles the conversion automatically — paste any number in any format and it outputs the correct international version. For a deeper dive into trunk prefixes and dialing conventions, see our guide on formatting numbers for international calling.

Why This Matters for WhatsApp

WhatsApp uses E.164 format internally. When you create a wa.me link:

https://wa.me/447911123456

That's E.164 without the +. If you include the trunk prefix or use the wrong country code, the link won't work — or worse, it'll open a chat with the wrong person.

Why This Matters for Developers

If you're building an application that handles phone numbers:

Store in E.164. Always. It's unambiguous and globally unique.
Display in international format. Add spaces and formatting for readability. A phone number formatter can handle this conversion consistently.
Accept any format. Users will enter numbers however they're used to. Parse and convert to E.164 on input. Consider adding validation to catch invalid numbers early.
Use a library. Don't write your own phone number parser — use Google's libphonenumber or an equivalent. Phone number formatting rules are complex and change regularly.

Converting Between Formats

Manual Conversion

To convert a national number to E.164:

Identify the country
Find the country code
Remove the trunk prefix (if applicable)
Combine: + + country code + number (no spaces)

Automatic Conversion

NumSwift converts any phone number format to international format automatically. Paste text containing numbers in any format — local, national, with or without country codes — and each extracted number is displayed in proper international format with one-click actions.

For a complete list of country codes and their formatting rules, see the International Phone Number Format Guide.

Related Guides

How to format any phone number for international calling — step-by-step instructions for exit codes, trunk prefixes, and the + shortcut
Phone number validation: how to check if a number is real — go beyond formatting to verify whether a number actually exists
International phone number format and country codes — complete reference for 200+ country codes and dialing conventions

Bottom Line

Local format is for calling your neighbor. National format is how most people write numbers. International format is for human-readable cross-border communication. E.164 is for machines — databases, APIs, WhatsApp links, and any system that needs an unambiguous phone number.

When in doubt, convert to E.164. And when you don't want to figure out the conversion yourself, NumSwift does it in one paste.