The first time anyone makes an international call, the question is the same: do I dial the plus sign, the 00, or just the country code? Why does my friend in London insist I “drop the zero” and what does that even mean? And once I get past the dialing, am I about to pay $14 for a five-minute conversation?
Here is the plain-English version. Three numbers, two examples, one comparison of how to actually pay for the call without overspending.
The three numbers you need to dial any international call
Every international call has the same shape, regardless of which two countries are involved.
[exit code] + [country code] + [local number, no leading zero]
That is it. The whole formula. The three pieces:
Exit code. This is your country’s “I want to dial out” prefix. In the US, Canada, and most of the Caribbean, it is 011. In almost everywhere else, it is 00. On a mobile phone in any country, you can usually replace the exit code with a + sign, and the network figures out the rest.
Country code. A 1-to-3-digit number assigned to the destination country. The US and Canada share 1. The UK is 44. India is 91. France is 33. There is a public list of all of them maintained by the International Telecommunication Union.
Local number, with the leading zero dropped. Many countries write their domestic phone numbers with a leading zero (UK landlines look like 020 7946 0000, Australian mobiles look like 0412 345 678). When you call from outside that country, you drop the leading zero. So 020 7946 0000 becomes 20 7946 0000 for international callers.
Why the leading zero gets dropped. The leading zero is a “trunk prefix” that tells your domestic network you are dialing long-distance within the country. Once you have already used the country code to specify which country you mean, the trunk prefix is redundant.
Worked example one: dialing the UK from the US
You want to call a London landline that locals would dial as 020 7946 0958.
| Piece | Value |
|---|---|
| Exit code (US) | 011 |
| Country code (UK) | 44 |
| Local number, zero dropped | 20 7946 0958 |
What you actually dial:
011 44 20 7946 0958
Or, on a mobile, the cleaner version:
+44 20 7946 0958
Both work identically. The plus sign is universal across the GSM network, which is what makes it the safer habit.
Worked example two: dialing India from the UK
You want to call a Bangalore landline that locals would dial as 080 2234 5678.
| Piece | Value |
|---|---|
| Exit code (UK) | 00 |
| Country code (India) | 91 |
| Local number, zero dropped | 80 2234 5678 |
What you actually dial:
00 91 80 2234 5678
Or:
+91 80 2234 5678
Same pattern. Two countries, two different exit codes, identical structure.
Calling from a mobile carrier vs from an app: the cost gap
Once you know how to dial, the next question is how much it will cost. This is where the gap between “what your carrier charges” and “what an app charges” becomes uncomfortable to look at.
A representative example for a 10-minute call:
| How you placed it | Approximate cost |
|---|---|
| Major US carrier, no international add-on | $4 to $20 |
| Major US carrier, with international add-on | $0.50 to $3 |
| WhatsApp call (recipient also on WhatsApp) | Free, but uses data on both ends |
| numeroesim VoIP calling credit | $0.10 to $0.40 |
| numeroesim local-rate plan to a virtual number | Often included in the monthly plan |
The carrier rate without an add-on is the worst option. The carrier rate with an add-on is the second worst. App-based VoIP and local-rate virtual numbers beat both by an order of magnitude. The full pricing-model breakdown is in the international calls plans buyer’s guide if you want the longer version of why.
For specific country pairs, the existing tutorials on calling Mexico from the US, calling the UK from the US, and calling Canada from anywhere walk through the country-specific quirks.
Numeroesim in three taps
If you want the cheap-VoIP option without leaving an article to figure it out, here is the abbreviated version:
- Install the numeroesim app from the App Store or Google Play, or visit numeroesim. Register with your real number.
- Go to Calling Plans and choose either Top Up for global pay-as-you-go credit, Local Calling Plans if you call one country regularly, or EU Calling Plans if you call across Europe.
- Open the dial pad, type the international number with the + sign, and tap call. Rates display before you connect, so there are no surprises.
The detailed walkthrough lives on the how to use Numero eSIM for calls and SMS page, and the recharge tutorial covers the credit side.
Common mistakes that cause “this number cannot be reached”
People get the dialing wrong in five predictable ways. If your call is failing, check these first.
Mistake 1. You kept the leading zero on the local number. Dialing +44 020 7946 0958 will not connect. Drop the zero: +44 20 7946 0958.
Mistake 2. You used your country’s exit code on a mobile and left out the country code. 011 7946 0958 is not a valid number anywhere. The country code (44 for the UK in this example) is mandatory.
Mistake 3. You used 00 from a US-based phone. US exit code is 011. Some apps accept the international 00, but the carrier dial pad usually does not. Default to the + sign, which works everywhere.
Mistake 4. You included the country’s national prefix when dialing inside the country code. India’s 0 for trunk dialing is the same case as the UK’s. Drop it.
Mistake 5. You are trying to call a premium-rate number (lottery hotline, satellite phone, certain support lines) and your plan does not allow them. These often need to be enabled separately or are excluded from international add-ons entirely.
FAQ
Does the plus sign work from a landline?
Usually no. The + sign is a GSM mobile feature. From a landline, dial the explicit exit code (011 in the US, 00 most other places).
Why are some country codes longer than others?
The International Telecommunication Union assigns country codes by region and historical allocation. Some small countries share a prefix (Caribbean countries are mostly +1), while others got their own short code (UK is +44, India is +91). The length is not a quality marker.
Can I receive international calls without paying anything?
Generally yes. In most countries, the caller pays. The recipient pays nothing, even on a mobile. Exceptions exist (some older US plans charge incoming international, and roaming abroad complicates this).
What does "ten ten" mean? My old phone bill mentioned it.
That is a US-specific carrier-bypass dialing prefix from the 1990s and 2000s. Largely obsolete in 2026.
Can I make international calls during a flight?
Only on flights with onboard Wi-Fi calling. Some airlines now allow VoIP apps to function over their in-flight Wi-Fi, although availability varies.
The short version
International calls are not complicated. The dialing format is [exit code or +] + [country code] + [local number with leading zero dropped]. The cost question is what trips most people up, and the answer is almost always “use VoIP credit, not your carrier.”
If you want to start placing cheap international calls today, topping up calling credit on numeroesim is the shortest path. The dial pad does the rest.
