Lost your SIM card while traveling, or living abroad and need to call home? Maybe your phone is broken and can't read a SIM right now. None of that cuts you off: if you can get online, you can still make calls.
There are two ways to do it: your phone's built-in Wi-Fi Calling feature, and dedicated Voice over IP (VoIP) apps. Both bypass the cellular network and route your calls over the internet. They differ in what they cost and what they can reach, especially for international calls.
Your SIM-free calling options
Either way, the thing you need is a stable Wi-Fi connection.
Wi-Fi Calling is already built into most modern smartphones. It lets you make and receive calls over a Wi-Fi network using your regular phone number, which helps when cell service is patchy but the Wi-Fi is strong, at home or in a hotel.
Calling apps such as CallSky (our product) use the internet (Voice over IP technology) to connect you to any landline or mobile number worldwide. WhatsApp and similar apps do the same for calls to other app users. For international calls they often cost a fraction of what traditional mobile carriers charge.
The decision tree below shows both paths.
Which one to use depends on what your phone can do and who you need to reach.
Calling without a SIM at a glance
| Feature | Built-in Wi-Fi Calling | VoIP Apps (e.g., CallSky) |
|---|---|---|
| Phone Number | Uses your existing mobile number. | Provides a new number or makes calls without one. |
| Best For | Domestic calls with poor cell service. | Affordable international calls, temporary phone use. |
| Setup | Simple toggle in your phone's settings. | Requires downloading an app and creating an account. |
| Cost | Usually included in your mobile plan (for domestic calls). | Pay-as-you-go or subscription; very low-cost for international. |
| Caller ID | Shows your normal phone number. | May show a different number or "Unknown." |
Wi-Fi Calling is the convenient choice for domestic calls. VoIP apps are cheaper and more flexible for calls to other countries.
Option 1: Use your phone's built-in Wi-Fi Calling
The easiest way to make a call without a cellular connection is a feature that's already on your smartphone: Wi-Fi Calling. Most modern iPhones and Android devices have it. It routes your calls over a Wi-Fi network instead of a cell tower.
It helps when your hotel has terrible reception or your phone can't connect to a mobile network. Once it's on, your phone switches to Wi-Fi for calls whenever it's connected. It also uses your regular phone number, so people see your usual caller ID and can call you back the same way. You don't need a new app or account.
How to enable Wi-Fi Calling
Turning it on takes less than a minute.
- On an iPhone, go to Settings > Phone > Wi-Fi Calling and turn it on.
- On Android, the path varies by manufacturer but is usually under Settings > Network & Internet > Calls & SMS or a similar menu.
For domestic calls where you have good Wi-Fi but a poor cell signal, Wi-Fi Calling is the best fit, and it needs no extra software.
For international travelers, though, it has a big drawback. If you use it to call another country, your mobile carrier will probably bill you at its standard international rates, which are expensive, because the call is still processed through your carrier. That's where VoIP comes in. Our guide on what Wi-Fi calling is goes into more detail.
Option 2: Use VoIP apps for global calls
For international calls, Voice over IP (VoIP) apps fill the gap that Wi-Fi Calling leaves. VoIP converts your voice into digital data and sends it over the internet, bypassing traditional phone networks entirely.
With a VoIP app you can call almost any landline or mobile number on the planet from a smartphone, tablet or computer. All you need is an internet connection, which is why it works for travelers, expats and anyone with a broken phone.
Why VoIP suits travelers and expats
The first reason is cost. International calls with a VoIP app like CallSky cost far less than mobile carrier rates, often just a few cents per minute.
A VoIP calling service can also dial any phone number, whether it's a mobile in Mumbai or a landline in London, and the person you call doesn't need the same app. App-to-app calling, such as WhatsApp to WhatsApp, can't do that.
You aren't tied to one phone, either. You can log into your VoIP account and call from a laptop, a tablet or a borrowed phone, which is useful in a pinch.
Some services also let you rent a virtual phone number, giving you a local number that friends, family or businesses can call without paying international fees.
Which method is best for international calls?
For calling internationally without a SIM, VoIP apps win. Your phone's Wi-Fi Calling is convenient for domestic use, but for calls abroad it often applies your carrier's expensive international rates. VoIP services were designed for cheap global calls.
Say you live in Spain and need to call your bank's 1-800 number in the United States. WhatsApp can't do that, and roaming on your mobile plan would be costly. With a VoIP service like CallSky, you open the app, dial the US landline number and connect over Wi-Fi. The call costs pennies per minute instead of dollars.
CallSky is pay-as-you-go. You top up your account with credit and use it as needed, with no monthly contract or hidden fees, and unlike many prepaid plans, the credit doesn't expire. It reaches landlines and mobile phones in over 180 countries.
Our guide on how to make international calls covers more ways to do it.
A warning about emergency calls
Calling over the internet has one major limitation you need to know about: emergency services.
When you dial 911 (in the US), 112 (in Europe) or your local emergency number, dispatch systems rely on the cellular network to pinpoint your exact location, and that can save a life. Calls made over Wi-Fi Calling or VoIP apps often can't provide that precise location data.
Why location accuracy fails over Wi-Fi
A phone on a cellular network is in constant contact with nearby towers, which gives emergency services a reliable lock on your position. An internet call only provides an IP address. That might identify the city you're in, but not the street or building where you need help, and the delay can be dangerous.
Don't rely on Wi-Fi Calling or VoIP apps for emergencies. Whenever you can, call for help from a phone with an active cellular connection. It's the most reliable way for first responders to find you quickly.
Common questions about calling without a SIM
Can people still call me if I don't have a SIM card?
Yes. With Wi-Fi Calling enabled, your phone rings on your regular number as long as you're connected to Wi-Fi, and the caller won't notice any difference. VoIP apps can receive calls too.
Can I call landlines and mobile numbers with these methods?
Yes, with both. Wi-Fi Calling works just like your normal phone dialer. Dedicated VoIP apps are built to connect to any standard landline or mobile number worldwide, which app-to-app services like FaceTime or WhatsApp can't do.
How much data does an internet call use?
Very little. A typical voice call over the internet uses about 0.5 MB to 1 MB of data per minute, so an hour-long conversation uses around 30 to 60 MB, a fraction of what video streaming needs. That makes it an efficient way to talk, even on slower public Wi-Fi networks.
CallSky is our product. It calls 180+ countries on pay-as-you-go credit that never expires, with no subscription.