How can a smartphone still make emergency calls?

The modern smartphone is a marvel of technology, packing enormous computing power and a variety of hardware components into a package that fits in the palm of your hand.

Over time, communication technology has developed by leaps and bounds, and today’s cell phones can even work in very remote locations. However, have you ever wondered how your phone can make emergency calls even if you have no network signal?

You may have seen the message “No network signal. Emergency calls only” appear on your phone. But how can your phone make emergency calls without a signal? Let’s find out!

How emergency calls work without a service provider

To understand exactly how emergency calls work, it is important to gain a full understanding of the basics of conventional networking. When you add a SIM card to a mobile device, it automatically searches for a connection.

The network provider provides this. The phone sends out a signal that connects to the cell tower closest to your location, established by your network provider. Once the first signal is connected, it is amplified and then relayed from tower to tower until it finally reaches the tower of the person you are calling.

This all happens within seconds and you can still see the signal strength represented by bars, usually in the top right corner of your phone. Today, while cell phone towers typically bounce signals from their own network for conventional calls, modern devices have technology that allows them to make emergency calls by bouncing signals from the turn of another network.


So when you make an emergency call, the signal searches for the nearest cell tower, regardless of which provider owns it.

Related: How to Track Cell Phone Location Using Phone Number Only

How Network Provider Authentication Works

A person holding their phone

As we have established, in the case of an emergency call, the signal does not need to be sent through a cell tower belonging to your carrier. In general, many carriers also simply rent cell towers from another company and offer their services.

But none of this is possible without network provider authentication. Think of it as a digital handshake that authorizes your phone to use the network in the first place, using your SIM card. Simply put, your phone is only capable of transmitting signals through mobile phone networks for which it has permission to do so.

So if you try to make an emergency call in a foreign country using your local SIM card, it just won’t go through (unless your existing carrier has an agreement in that country). These calls are usually handled differently anyway, as they are routed to the nearest dispatch center first.

Related: Ways Your Cell Phone Can Be Hacked – Are You Safe?

Therefore, when you are in another country and you have not yet switched to a local SIM card, you will not be able to make emergency calls either. You may just get a message saying “No Service”. This happens when the network does not recognize your device.

This can happen in some remote parts of the country, where there may be a local network that could service your phone, but since they may not have a contract with your carrier, they simply refuse to do so.

Can you make an emergency call without service?

Most cell towers across the country are now equipped with E911 (enhanced) receivers. Many disabled towers do this too. The FCC has regulations to ensure that 911 calls are accepted by all providers, even if you don’t have a phone plan.

This feature was introduced when the GSM standards were created in the 1990s. You can make an emergency call without service, as long as there is a cell tower nearby and you are using a local SIM card.

You don’t need a paid subscription or phone plan to make an emergency call. However, if you are in another country, or if there are no cell towers nearby, there is simply no tower the signal can lock onto. If you are completely out of the network, you cannot make an emergency call.

Related: CDMA vs GSM: What’s the difference and which one does your phone use?

FCC Rules for 911 and Emergency Calling

The Wireless Communications and Public Safety Act, better known as Law 911, came into effect in 1999, establishing a nationwide emergency response system. This required all carriers to accept 911 calls throughout their network.

This system is updated regularly, with E911 upgrades in progress. Improved 911 capabilities now also report location and phone number whenever an emergency call is made. Whenever an emergency call is made, it is instantly routed to a Public Safety Answering Point (PSAP).

The FCC began collecting data in 2003 for PSAPs and assigning them identification numbers. Today, this network is used throughout the country. In 2019, pursuant to Section 506 of the RAY BAUM Act, the FCC also implemented rules that transmit a caller’s dispatchable location to 911.

Using another provider to make emergency calls

Image of a cell tower and a maintenance worker on a boom lift

If you don’t have bars on your phone, it just means there are no towers nearby that support your carrier. But, when you make an emergency call (either from the dialer or from the lock screen), the authentication process changes.

For such calls, the signal may overlap with the infrastructure of another network provider. An interesting chain of events triggers when you make an emergency call under such circumstances.

The in-house phone software quickly scans available signals in the area and identifies the strongest to answer the emergency call. This emergency call is then tagged, giving it priority as specified by FCC guidelines.

You don’t even need a SIM card in your phone for this to happen! The priority beacon is very important because if the cell tower is operating at its maximum capacity, it will simply push back a call without priority status to allow an emergency call to connect.

It seems like a lot of things are happening at once, but know that it all happens in seconds! That’s why you get such a quick response when dialing an emergency number in most cases.

Emergency response services are improving

The FCC continues to design and implement rules that improve the reliability and efficiency of emergency calls. With the advent of advanced communication technologies, including 5G, mobile operators are also developing new technologies and upgrading existing networks to provide better support to people across the country.

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