Free phone number tools
Short answer: Two free tools for working with international phone numbers: a table of country calling codes and number lengths for 181 countries, and a formatter that turns a number written the local way into the international E.164 format that apps and SIP systems expect.
Handy references for anyone who saves, dials or configures phone numbers across countries. Both tools run in your browser, need no account and use the same country data as our number pages.
- Country calling codes — Codes, number lengths and E.164 format for 181 countries.
- Phone number formatter — Convert a local number to E.164 and check its length.
The tools at a glance
| Tool | What it does | Use it when |
|---|---|---|
| Country calling codes | Lists the calling code, digits after the code, full E.164 length and an example format for 181 countries | You need to know how a number from another country is built |
| Phone number formatter | Converts a number written the local way into E.164 and checks its length for the chosen country | You are about to paste a number into an app, a contact card or a PBX |
Country calling codes
Every country has a calling code of one to three digits: +1 for the United States and Canada, +44 for the United Kingdom, +91 for India. After the code comes the national number, whose length depends on the country and sometimes on the number type. The country codes table shows both for all 181 countries where ZuteSIP has real numbers, with a link to each country's numbers.
Phone number formatter
Numbers are usually written differently at home than they must be entered in apps. A UK mobile written 07700 900123 becomes +447700900123 in E.164: the leading 0 (the trunk prefix) goes, the country code is added and spaces disappear. The formatter does this for you and warns you when the digit count doesn't match what is usual for that country. It only checks the format; it doesn't look the number up on any network, and nothing you type is sent anywhere.
When you need these tools
- Saving international contacts so they work from any country
- Entering a number correctly when an app asks you to verify it
- Configuring caller ID and routes in a SIP softphone or PBX
- Checking that a number from another country has the right number of digits
From format to a working number
If you need a real number in another country rather than just its format, ZuteSIP has mobile, local and toll-free numbers in 181 countries from $1.80 per month, billed yearly ($21.60 per year). Every number includes unlimited incoming SMS and calls, SIP credentials and a web dialer, and comes with a 7-day replacement guarantee.
Frequently asked questions
Are the tools free?
Yes. Both tools are free and run in your browser without an account.
What format do apps expect?
Most apps and SIP systems store numbers in E.164: +, the country code and the national number, without spaces or a leading 0.
Does the formatter check whether a number is active?
No. It checks the format and length only; it doesn't query any network.
Where does the country data come from?
From the same country list, dialling codes and number lengths used on our number pages.
Related pages
- What is E.164?
- What is SIP?
- Phone numbers by country
- SIP dialer
- Glossary
- How to get a phone number in another country
Sources
- ITU-T Recommendation E.164 (as of September 2026)