Why proper international phone number formatting matters
When sending bulk SMS or running WhatsApp marketing campaigns across borders, getting phone number formatting right is essential. Using the correct format ensures your messages are delivered reliably, improves campaign performance, and avoids extra costs from failed sends.
What is the international E.164 phone number format?
The globally accepted format for international phone numbers is E.164. This standard is recognized by all major telecoms, messaging providers, and APIs. E.164 numbers look like this:
- A plus sign (+)
- Country code (1–3 digits)
- Subscriber number (national significant number)
For example, a Belgian number in E.164: +32479123456
Step-by-step guide to formatting international numbers
- Remove leading zeros: Many national formats use a leading ‘0’ in the area code. For E.164, this must be removed.
- Add the country code: Make sure you use the correct country code. For Belgium, it's “32”; for the UK, “44”; for Germany, “49”, and so on.
- Keep only digits after the country code: Do not add spaces, dashes, or parentheses.
- Prefix with a plus (+): The E.164 format starts with a “+”. Some systems may require “00” instead, but most APIs—including SmsTools SMS API—require “+”.
Examples of converting to E.164
- Belgium: 0479 12 34 56 → +32479123456
- Germany: 0171 1234567 → +491711234567
- France: 06 12 34 56 78 → +33612345678
- UK: 07911 123456 → +447911123456
Formatting tips by country
Each country has its nuances. Our SMS software can help detect and clean phone numbers, but here are some quick guides for the most common European countries:
- Netherlands: NL local 0612345678 → +31612345678 (drop any leading '0')
- Italy: IT local 3281234567 → +393281234567
- Spain: ES local 612345678 → +34612345678
- Portugal: PT local 912345678 → +351912345678
- Poland: PL local 512123456 → +48512123456
Common formatting mistakes to avoid
- Using local prefixes (like 0) after the country code
- Adding spaces or punctuation in the number string
- Forgetting the plus sign or using incorrect country codes
- Mixing local and international formats within your list
Automate and validate number formatting
To save time and prevent errors, use Make.com or Zapier integration to clean and standardize numbers before sending. Smstools also offers easy-to-use bulk import tools to fix common issues.
Special cases and advanced tips
- For two-way SMS, use virtual SMS numbers compatible with your target country.
- For WhatsApp, always use E.164 format when submitting numbers to the WhatsApp newsletter platform.
- Add a validation step in your onboarding forms to check number formatting immediately.
Correct formatting is crucial for transactional alerts, OTP SMS, marketing broadcasts, and service notifications. Let Smstools optimize deliverability for you—try our platform now: REGISTER
FAQ: international number formatting
What is E.164 format?
E.164 is the standardized format for international phone numbers. It starts with a "+", followed by the country code, then the subscriber number, with no spaces or dashes.
Can I send SMS if the number is not in E.164?
Some local messages may still be delivered, but international and API-based campaigns require E.164 for the best results.
How can I check if my numbers are formatted correctly?
Use the Smstools import tool or automate validation via Make.com or Zapier.
What about double country codes?
Never add multiple country codes (e.g., +324479123456). Only add the correct international prefix once.
Do I need E.164 for WhatsApp newsletters?
Yes—WhatsApp only accepts phone numbers in E.164 format for sending messages at scale.
Need help setting up your database? Start a free trial and use our support tools to ensure perfect formatting!