In this article, we’ll discuss some of the common terms used when referencing mobile phones, connectivity, and cellular devices. These terms are not intended to be completely comprehensive, but, intended to be a starting point to give you context on phone terminology.

This list may be updated in the future.

What's a SIM card?

SIM stands for "subscriber identity module". SIM cards give you the ability to access a carrier's network, data, text SMS, phone service, and internet usage. These plans could range from regional to international data packages and price points.

SIM cards also act as two-step verification for the carrier. 1), they're able to identify the user with a cellular license plate, and 2), the carrier is also able to verify if your SIM is compatible with their networks.

What's a Dual SIM?

A Dual SIM card refers to a mobile phone or device that supports the ability to house more than one SIM on the phone at any given time. Whether this is an embedded SIM or physical SIM card, your device has the built-in option of changing network providers.

The reason this is important for the wireless consumer is that carriers can be restricting in determining who is eligible to connect to their mobile network. Say you're a traveler with an American number and American carrier support, your device may be unable to connect to the local French telecom network when you land. Having the ability to transfer or swap to another chip allows you to remain connected, call, download, and text in regions outside of your primary SIM.

What's an eSIM?

eSIM stands for an "embedded" SIM card. Because the eSIM is embedded into the device, this now gives you the option to download SIMs directly to your device instead of switching out chips.

If you're looking to download an eSIM, here is our list of all the compatible devices that support an eSIM: Here

eSIMs also give you the same connectivity as a physical SIM card, by allowing you to:

  • Use your mobile network for local data
  • Cellular service to call, contact and remain connected to other phones and devices
  • Connect, screen, scan, store, search, activate, and download data to your device
  • Keep your number while still being able to switch your phone line
  • Never have to worry about being hit with roaming charges
  • Download and pay for a plan that makes sense for your data needs
  • Activate your eSIM plan with a QR Code instead of inserting a chip
  • Tap the Airalo app to switch your data plan to a local, continental or international plan
  • Max usage by choosing subscriptions to shorter plans all the way to longer plans (based on need)

What's data roaming?

Data roaming is when you connect to the internet through another mobile provider while being billed by your original provider. Remember when I mentioned that your SIM verifies you and what networks you're allowed to use? This is where roaming comes in.

Say you happen to travel from the US to France, and you forgot to set up an international or French mobile plan with your carrier, any data you use overseas will be charged as "roaming".  This means any business you conduct, search, Google, scan, purchase in the store, or bar menu you browse will cost you at a max international rate.

With Airalo, our eSIM plans can be setup up through the app, and with a tap of the screen, you will never be charged again for data roaming by your main provider. If you have an eSIM capable device, it's a time saver.

What's a network?

Broadly speaking, a network is a series of interconnecting nodal points that align a series of interconnecting channels. In the context of telecommunications, a cellular or telecom network is a series of service towers that give you access to data, phone, and carrier service. These could be things like making a call from your phone, texting a friend, or having data to browse online.

Different carriers own, operate, and outsource connectivity to various providers. Think of a telecom network like owning ports in a city. The owner of the port decides who has access and what the cost per access is. In cases where your network is not within the telco's range, you will be given access, but charged a premium for the service (known as roaming).

What's local data?

Local data is information that is wholly stored directly on your device. This is information that takes up space on your phones like apps, photos, movies, music, etc. This data can be managed directly in your settings and by going through the data storage menus.

Occasionally, local data will overlap with cellular service from your provider. SMS contacts and records can be stored on your phone or device, including call history, and data downloaded over your provider's network.

What's an app?

App is short for "application".  Applications are typically programs downloaded directly to your phone. or your mobile device. The term is interchangeable with programs or software but has been commonly used when discussing mobile devices.

What's the difference between a 3G, 4G, and 5G networks?

3G, 3rd generation networks, refers to the common name of cellular towers that offer 2mbps for stationary activity and 384kbps when on the move (like a vehicle). They are relatively common amongst networks already in place but are becoming more outdated as new generations are replacing them.

4G, 4th generation networks, are the successor to 3G networks, are on average 500X faster than 3G networks, offering 10-100Mbps download speeds. Introduced in the late 2000s, their exponential difference in speed has slowly become standard across most global areas of coverage.

5G, 5th generation networks, are the successor to 4g networks by using unparalleled low latency and high bandwidth, 5G is far faster than 4G. This could mean streaming videos in 4k, downloading huge files, and sharing information at record speeds.

What's a VoIP?

VoIP stands for voice over internet protocol. VoIP allows you to place and receive calls over the internet. Traditionally, this was used as dial-up modems were commonplace in the 1990s. Then, the easiest way to communicate was through a series of phone lines and peer-to-peer network computers to connect to the net.

Now, VoIPs are used for secure calling communications across the internet. Typically these are used for business calls, personal calls, and general audio/video communication.

What is Mbps?

Mbps stands for Megabytes per second. It describes the bitrate you can download at and also upload at. Mbps is the most common as it is the most ubiquitous speed since most data does not transfer at a kilobyte, gigabyte, or terabyte rate. Gbps and Tbps might become common terms in the next few years.

What do pixel ranges mean?

Pixel ranges describe the dimensions of a device's pixel density. For example, 1080p by 1920p (pixels) is standard for high definition. This means that the screen can display the given amount of pixels length-wise and width-wise. To note, pixel ranges can also describe the max and minimum rage the device can display pixel resolution.

Looking for more phone terms and definitions, email growth@airalo.com to suggest new terms (we're always looking for more!)