PrepaideSIM Glossary: 26+ Terms Every Traveler Should Know
- 26 terms defined
- Plain language
- Traveler-focused
- Updated June 2026
Daniel Mercer
Lead eSIM Analyst
Previously at Analysys Mason covering APAC mobile markets (2016-2021)
How we testPublished June 2026 · Updated June 2026
Section A-D
A-D: 5 terms.
- APN (Access Point Name)
- A network gateway that connects your phone to the internet through a specific carrier. eSIM providers configure the APN automatically during installation. You rarely need to set this manually.
- Carrier Lock
- A restriction placed by a mobile carrier that prevents a phone from using SIM or eSIM profiles from other carriers. A carrier-locked phone must be unlocked before installing a travel eSIM from a different provider.
- Data Roaming
- Using your home carrier's data plan while connected to a foreign network. Carriers charge roaming fees of $5-$15/day. A travel eSIM avoids roaming fees by connecting directly to a local network.
- DSDS (Dual SIM Dual Standby)
- A phone mode that keeps two SIM lines active simultaneously but only allows one to carry data at a time. Most modern dual SIM phones use DSDS. You assign one line to data and one to calls.
- Dual SIM
- A phone that supports two active SIM profiles at the same time. This can be two physical SIMs, one physical SIM and one eSIM, or two eSIMs. Dual SIM lets travelers keep their home number while using a local eSIM for data.
Section E-I
E-I: 5 terms.
- eUICC (Embedded Universal Integrated Circuit Card)
- The physical chip inside your phone that stores eSIM profiles. The eUICC can hold multiple profiles and switch between them without swapping hardware. It is the technology that makes eSIM possible.
- eSIM (Embedded SIM)
- A SIM chip built into a phone that downloads carrier profiles digitally instead of using a physical card. eSIMs support multiple profiles, remote provisioning, and instant activation. Supported on iPhone XS and later, Samsung Galaxy S20 and later, and Pixel 3 and later.
- Fair Use Policy
- A limit on high-speed data imposed by providers who advertise unlimited plans. Holafly applies a fair-use threshold of approximately 5 GB per day. After the threshold, speeds reduce to 1 Mbps. You are not cut off, but streaming and downloads slow significantly.
- ICCID (Integrated Circuit Card Identifier)
- A unique 19-20 digit serial number that identifies a specific SIM or eSIM profile. Each eSIM installation has a unique ICCID. Providers use it to look up your account and troubleshoot issues.
- IMEI (International Mobile Equipment Identity)
- A 15-digit number that uniquely identifies your phone hardware. Some countries (like Turkey and Egypt) require IMEI registration for foreign devices. You can find your IMEI by dialing *#06# on any phone.
Section J-P
J-P: 6 terms.
- LPA (Local Profile Assistant)
- Software on your phone that manages eSIM profile downloads, installations, and switches. The LPA communicates with the SM-DP+ server to download your eSIM profile. You interact with the LPA through your phone's cellular settings.
- LTE (Long Term Evolution)
- The 4G mobile network standard used worldwide. LTE provides download speeds of 20-100 Mbps in most urban areas. Most travel eSIM plans connect to LTE networks. 5G is available in select countries but is not required for typical travel use.
- MNO (Mobile Network Operator)
- A company that owns and operates mobile network infrastructure. Examples include Vodafone, T-Mobile, Orange, and NTT Docomo. MNOs own the cell towers. eSIM providers partner with MNOs to provide local network access.
- MVNO (Mobile Virtual Network Operator)
- A carrier that provides mobile service using another company's network infrastructure. MVNOs lease access from MNOs. Some eSIM providers operate as MVNOs. Performance depends on the underlying MNO and the MVNO's traffic priority.
- NFC (Near Field Communication)
- Short-range wireless communication used for contactless payments and some eSIM transfers. iPhone supports eSIM transfer via NFC between two iPhones held close together. This is an alternative to QR code installation.
- Profile
- A digital package containing your carrier information, network credentials, and plan details stored on the eUICC chip. Each eSIM installation creates one profile. You can store multiple profiles and switch between them.
Section Q-S
Q-S: 5 terms.
- QR Provisioning
- The standard method for installing an eSIM profile. A QR code containing the SM-DP+ server address and activation code is scanned by your phone's camera. The profile downloads automatically. Most eSIM providers use QR provisioning.
- Regional Plan
- An eSIM plan that covers multiple countries in a geographic region with a single data pool. Airalo Eurolink (Europe, 39 countries) and Airalo Americas (18 countries) are examples. Regional plans eliminate the need for separate per-country purchases.
- Roaming
- Connecting to a mobile network outside your home carrier's coverage area. International roaming on a home carrier plan is expensive ($5-$15/day with US carriers). A travel eSIM avoids roaming by connecting directly to a local network at local rates.
- SIM Lock
- A carrier-imposed restriction that prevents a phone from accepting SIM or eSIM profiles from other carriers. SIM-locked phones must be unlocked (by the carrier or a third party) before a travel eSIM can be installed. Most carriers unlock devices after the contract is paid off.
- SM-DP+ (Subscription Manager Data Preparation+)
- A server operated by the eSIM provider that prepares and delivers eSIM profiles to your phone. When you scan a QR code, your phone contacts the SM-DP+ server to download the profile. You never interact with this server directly.
Section T-Z
T-Z: 5 terms.
- Tethering
- Sharing your phone's data connection with other devices via WiFi hotspot, Bluetooth, or USB. Airalo, Saily, and Nomad allow tethering. Holafly blocks tethering on most plans. Tethering drains your phone battery 2-3x faster.
- Top-Up
- Adding more data to an existing eSIM profile without reinstalling. Airalo and Nomad support in-app top-ups. You buy additional data, and it adds to your current balance on the same profile. This avoids the need to install a new eSIM.
- UICC (Universal Integrated Circuit Card)
- The broader category of smart card technology that includes both physical SIM cards and embedded eSIM chips. The UICC stores subscriber identity, authentication keys, and contact information.
- VoIP (Voice over Internet Protocol)
- Technology that transmits voice calls over the internet instead of the traditional phone network. WhatsApp calls, FaceTime, Skype, and Zoom all use VoIP. VoIP works over any data connection, including eSIM data. Some countries block VoIP.
- VPN (Virtual Private Network)
- Software that encrypts your internet traffic and routes it through a server in another location. Saily includes NordVPN with every plan. VPNs protect your data on public WiFi but are restricted or illegal in some countries (UAE, China).
Practical Impact
How these terms affect your eSIM choice.
Most travelers need to understand only a handful of these terms. The rest are background knowledge that helps when troubleshooting or comparing providers. Here is what matters most for buying decisions.
Before you buy
Check that your phone is carrier-unlocked and supports eSIM. Verify the plan supports tetheringif you want to share data. Understand the provider's fair use policy if the plan is labeled unlimited.
During installation
You will encounter QR provisioning(scanning a code to download the profile). Your phone's LPA handles the download automatically. The APN configures itself. You should not need to enter any settings manually with major providers.
While traveling
Dual SIM and DSDS let you keep your home number active while using eSIM data. If your destination requires IMEI registration (Turkey, Egypt), check the rules before arrival. If VoIP is blocked (UAE, Saudi Arabia), plan for alternative calling methods.
If something goes wrong
Your ICCID is the key identifier for support requests. The SM-DP+ server handles profile re-downloads if you accidentally delete your eSIM. Your IMEI confirms device compatibility. Having these numbers accessible speeds up any troubleshooting process.
FAQ
eSIM terminology: common questions.
What is the difference between eSIM and SIM?
A SIM is a removable plastic card that stores your carrier profile. An eSIM (embedded SIM) is a chip soldered into your phone that downloads carrier profiles digitally. Both serve the same function — identifying you on a mobile network — but an eSIM eliminates the physical card and allows multiple profiles on one device.
What does data-only eSIM mean?
A data-only eSIM provides internet access without a phone number, voice minutes, or SMS. Messaging apps like WhatsApp and iMessage work over data. Traditional phone calls and text messages do not. Most travel eSIMs are data-only because travelers keep their home SIM for calls.
What is an ICCID number?
ICCID stands for Integrated Circuit Card Identifier. It is a unique serial number (19-20 digits) that identifies your SIM or eSIM profile. You can find it in Settings > About on most phones. Providers use it for troubleshooting and account lookup.
Can I use two eSIM profiles at the same time?
On iPhone 13 and later, you can have two active eSIM lines simultaneously (Dual eSIM). Older iPhones support one active eSIM plus one physical SIM. Most Android phones support one active eSIM plus one physical SIM. Check your specific model for dual eSIM support.
What is QR provisioning?
QR provisioning is the standard method for installing an eSIM. Your provider sends a QR code (by email or in their app). You scan it with your phone's camera in the cellular settings. The QR code contains the server address and activation code needed to download your eSIM profile.
Ready to get started? Compare plans now.
200+ countries. From $2.50/GB. No jargon required.