Technology background

What an eSIM actually is, and how it really works

If you have heard the word eSIM but never had it explained properly, this page is the explanation. No hype, no acronym soup for its own sake — just the chip, the standard that provisions it, the devices that support it, and the regulatory ground it sits on. Read it once and you will be able to hold your own in any conversation with a supplier or a technical team.

Definition

An embedded chip, not a plastic card

An eSIM is a chip, not a card. Technically it is an eUICC — an embedded Universal Integrated Circuit Card — a small, tamper-resistant secure element soldered directly onto the device's mainboard in the factory. It holds the same cryptographic identity material as a plastic SIM and performs the same function: it authenticates the device to a mobile network. What it removes is everything physical. There is no tray to open, no card to punch out, no stock to hold, nothing to ship and nothing to lose.

A physical SIM is a removable smart card in one of three mechanical formats — mini, micro or nano — that the customer inserts into a slot. Changing operator means changing the card. Buying a travel SIM at the airport means finding a shop, presenting ID and swapping the card over. An eSIM replaces that whole ritual with a download. The operator's profile — its identity, its keys and its rate plan — is delivered over the internet to a chip that is already inside the phone.

Because the eUICC is soldered in and standardised by the GSMA, it can hold several profiles at once and switch between them in software. A traveller can leave a home line active for calls and messages while running a local data profile for the trip, and can remove or reinstall profiles without touching any hardware.

For a business, the practical consequence is that connectivity becomes a software product. It is created on demand, delivered instantly, priced per unit and reconciled in a billing system — rather than being a stock item with a shelf life, a freight cost and a customs declaration attached to every unit.

The three things that actually change

  • Delivery. A profile arrives as a QR code or an install link, not as a parcel.
  • Flexibility. One device can hold multiple operator profiles and switch between them in software.
  • Ownership. The chip belongs to the device; the profile is a subscription that can be issued, revoked and re-issued remotely.
The short version

Same security model as a SIM card, none of the physical supply chain. That is the entire idea, and it is why eSIM changes the unit economics of selling travel connectivity.

Physical SIM

  • Removable card, mechanical slot
  • Stock, freight and customs
  • One operator at a time

eSIM

  • Soldered eUICC, no slot
  • Delivered over the air
  • Several profiles, software switching
How it works

Remote provisioning, step by step

Remote SIM provisioning (RSP) is the mechanism that puts an operator profile onto a chip the customer cannot physically reach. For consumer devices the governing specification is GSMA SGP.22. Five things happen, in this order.

1

The operator builds a profile

The MNO or MVNO — or a wholesale platform operating as an MVNO — creates a subscriber profile: IMSI, authentication keys, network access rules, data allowance and validity period.

2

SM-DP+ stores it securely

The profile is encrypted and held on an SM-DP+ (Subscription Manager — Data Preparation plus), the GSMA-certified server that prepares, stores and delivers profiles. What leaves the server is a binding: an activation code and a matching ID.

3

The customer gets a QR code or link

Nothing is shipped. Your customer receives a QR code, a one-tap install link, or an in-app push. The code contains the SM-DP+ address and a matching ID — never the profile itself, so a screenshot alone is not a usable credential.

4

The profile downloads over the air

The device contacts the SM-DP+, authenticates with its own EID, and pulls the encrypted profile down over Wi-Fi or mobile data — before departure, at the airport or on arrival. There is no network visit and no SIM swap.

5

The LPA installs and enables it

The LPA (Local Profile Assistant) built into the device operating system decrypts, installs and enables the profile. The handset now holds a network identity, and the operator's core network sees an ordinary subscriber.

The vocabulary you will hear in every technical conversation

eSIM
The industry's shorthand for the embedded SIM: the chip plus the remote provisioning system around it. Strictly speaking the chip is the eUICC; "eSIM" is the commercial name.
eUICC
Embedded Universal Integrated Circuit Card. The soldered secure element that stores and runs profiles. The GSMA specifications define how it is built and managed.
Profile
The operator's subscription in software form: identity, credentials, policies and tariff. Installing a profile is the eSIM equivalent of inserting a SIM card.
SM-DP+
Subscription Manager — Data Preparation plus. Prepares, stores and delivers profiles to devices. It is the server your platform talks to when it issues an order. In the older M2M architecture the equivalent role was split with an SM-SR (below).
SM-SR
Subscription Manager — Secure Routing. In the earlier GSMA M2M architecture (SGP.02) it carried management commands to the eUICC over the air. The consumer SGP.22 model that travel eSIMs use removes it from the consumer flow, which is one reason consumer provisioning is simpler than the M2M generation.
LPA
Local Profile Assistant. The software on the device that downloads, installs, enables, disables and deletes profiles. It is what makes the customer able to self-install without a shop visit.
EID
eUICC Identifier. The unique, permanent serial number of the embedded chip inside a specific device. It identifies the hardware — not the subscription — and is what the SM-DP+ uses to bind a profile to the right device.
ICCID
Integrated Circuit Card Identifier. The serial number of the profile itself. It is printed on a plastic SIM, and in an eSIM it exists only as data — which is why it is the reference you will quote when you raise a support ticket.
QR activation code
The scannable code handed to the customer. It encodes the SM-DP+ address and a matching ID, and is the fulfilment artefact that replaces a shipped card and a printed PIN letter.
Matching ID
The one-time token inside the activation code that points the device to one specific prepared profile on the SM-DP+. It is the join between your order record and the profile on the server.
Comparison

eSIM versus physical SIM, honestly compared

Both formats authenticate a device to a network. The differences are entirely in the supply chain, the customer experience and the compliance burden — which is where your operating cost lives.

DimensioneSIMPhysical SIM
Inventory None. Profiles are digital and issued on demand, so there is no dead stock and no forecast risk on a season you cannot predict. Physical stock sitting in a warehouse, a shop or a distributor's shelf, with a shelf life, shrinkage and write-off risk.
Logistics Nothing shipped. Delivery is a QR code or install link by email, app, voucher or printed card. Picking, packing, courier, tracking, failed deliveries and returns — per unit, per order.
Customs Not applicable. No goods cross a border, so there is no declaration and no clearance delay. Declarations, duties and clearance delays on cross-border shipments, plus the risk of a consignment being held.
Activation time Typically minutes. The customer installs before departure over Wi-Fi or on arrival, at any hour, without a shop visit. Requires physical insertion. At a destination this often means locating a shop, queueing and presenting identification.
Swap and replacement The profile is revoked from the console and re-issued remotely. The customer never waits for a delivery. A replacement must be picked, shipped and received — days of downtime and a real cost per incident.
Real-name registration burden A data-only travel profile carries no local number, so it generally falls outside local SIM registration regimes. This must be confirmed market by market, not assumed. Frequently requires local ID or passport registration, sometimes in person, and the obligation falls on whoever sells the card.
Environmental footprint No plastic, no punched carrier, no packaging, no air freight. Plastic card, carrier, packaging and freight for every single unit sold.
Suitability for corporate bulk Scales per traveller with no procurement lead time; consolidated billing and usage visibility across the whole workforce. Bulk stock, distribution, tracking and reconciliation overhead on every trip, with no central usage view.

The two formats are not mutually exclusive. Most partners we work with run eSIM as the default and keep a physical SIM line for customers whose handsets do not support an embedded chip — the same rate card, the same API, two delivery formats.

Devices

Which handsets can actually use an eSIM

Support is now broad enough that eSIM-only marketing is a reasonable default for most travel audiences — but not for all of them. Here is the honest picture.

Apple

Every iPhone from the XS and XR onwards supports eSIM. That covers essentially the entire active iPhone base in a typical travel market.

Samsung

Most Galaxy S20-and-later flagships, the Z Fold and Z Flip families and the recent Note and A-series models carry eSIM support.

Google

Pixel 3 and every later generation. Google has been among the most consistent supporters of the standard.

Everyone else

Huawei, Xiaomi, OPPO, vivo, Honor and Motorola support is growing quickly, particularly on flagship and upper mid-range models.

Twelve markets where there is no SIM tray at all

This is the development that turns eSIM from a convenience into a necessity. Apple has now removed the physical SIM tray entirely in twelve markets. A traveller who buys their handset in any of them has no slot to put a local SIM card into — for inbound visitors from those markets, an eSIM is not the better option, it is the only option.

It also works in the other direction. A customer in one of those markets who travels without arranging data before departure has no fallback: there is no airport kiosk that can help them.

United States Canada Mexico Japan Guam US Virgin Islands Bahrain Kuwait Oman Qatar Saudi Arabia United Arab Emirates

Source: MacObserver — the full list of eSIM-only markets.

What this means when you sell

  • For inbound travellers from those twelve markets, offer eSIM first — there is no physical alternative to fall back on.
  • Ask one qualifying question at checkout: handset model. It separates the eSIM-only customers from the ones who still need a card.
  • Keep a physical SIM line for older handsets and for corporate buyers with mixed device fleets.
  • Pre-departure is the moment of sale. Once the customer is airside, the only install path is Wi-Fi — and the only competitor is the airport kiosk.
Standards

SGP.22 and SGP.32 are not the same thing

One of these powers every consumer travel eSIM sold today. The other is an IoT specification that is only now reaching commercial deployment. Suppliers sometimes blur the two. Do not let them.

SGP.22 — consumer RSP

The standard that travel eSIMs actually run on. Profiles are pulled to a device by the person holding it: they scan a QR code or tap an install link, and the Local Profile Assistant on the phone downloads and installs the profile.

It assumes a device with a user interface and a human to drive it. Profile switching is manual — the customer decides which line is active, and the handset's own settings screen carries the controls.

Mature, widely certified, and the basis on which every mainstream travel eSIM product — including ours — is delivered today.

SGP.32 — IoT RSP

The specification for devices with no screen and sometimes no user at all. It adds an eSIM IoT Manager (eIM) and an IPA, the IoT Profile Assistant, so that a fleet operator can provision, switch and manage profiles across thousands of devices from one platform.

Nothing has to be scanned. A tracker, a meter, a connected vehicle or an industrial gateway can be re-provisioned remotely, by software, at scale — which is exactly what the earlier M2M generation struggled to do efficiently.

Commercially important for fleet and IoT buyers. It is not what a consumer travel eSIM runs on.

Where SGP.32 actually stands

First commercial SGP.32 launches began in the second half of 2025, and Kaleido Intelligence forecasts roughly 50 million SGP.32-compliant eSIMs to be managed globally by 2027 — a meaningful fleet number, but a fraction of the consumer base and still ahead of most deployments.

Source: Kaleido Intelligence, via The Fast Mode. For a plain comparison of the SGP.02, SGP.22 and SGP.32 generations, see Onomondo's technical summary.

Be careful how SGP.32 is sold to you

SGP.32 is not yet a mature consumer proposition. It is an IoT specification with a small number of early commercial deployments, and the consumer ecosystem — device certification, carrier support, the app layer a traveller would touch — is not there.

If a supplier offers you SGP.32 as a live, consumer-ready capability for a travel product, ask for the named commercial deployment it is running on, in production, with volumes. If there is no name, there is no deployment, and what you are being sold is a roadmap.

For a travel eSIM business today, the standard you are actually buying is SGP.22.

Regulation

Data-only versus voice and SMS — and why the difference is commercial

Most travel eSIM products are data-only, and that is not an accident of technology. It is a compliance position with a direct effect on your operating cost.

Mandatory SIM registration is now the norm rather than the exception: more than 155 countries have SIM registration laws in force, together covering over 60% of global mobile connections, according to the GSMA's regulatory tracker. Those regimes exist to attach a verified identity to a mobile number.

A data-only travel profile is issued no local phone number — no MSISDN. The registration obligation attaches to the assignment of a local number, so a profile that never receives one generally sits outside the regime. That is a structural advantage rather than a loophole, but it is not self-certifying: the rules differ by market, and some jurisdictions write them more broadly than others. It has to be confirmed country by country, which is work a wholesale supplier should do on your behalf.

Voice and SMS are available as an option in selected markets. Where you take them, a local number is assigned, and with it the registration duties come back — as does the ability to serve customers who genuinely need a local number for calls or verification codes. The trade is explicit: reach versus compliance overhead.

Source: GSMA — mandatory SIM registration guidance.

Hong Kong: a concrete argument for the eSIM route

Hong Kong's registration regime under the Telecommunications (Registration of SIM Cards) Regulation (Cap. 106AI) caps how many pre-paid SIM cards one subscriber may hold with a single operator:

  • Individuals: up to 10 pre-paid SIM cards per operator.
  • Corporates: up to 25 pre-paid SIM cards per operator.
  • Service-plan SIMs (SSP): no cap — the quota applies to pre-paid cards, not to subscription-plan SIMs.

For a distributor, an agency or a corporate travel desk that needs to equip hundreds of travellers, that cap is a hard ceiling on the physical-card route unless every card is registered against a named individual. A data-only eSIM profile carries no local number and no pre-paid SIM registration quota in the same way — which is why corporate channels that have hit the ceiling are the fastest-moving adopters of the eSIM format.

Source: OFCA — SIM card registration. Registration rules change; confirm the current position for your market before you rely on it in a contract.

What to ask a supplier before you commit

  • Is the profile data-only, or does it assign a local number?
  • Who is the legal seller of record, and who carries the registration duty in each market?
  • If voice or SMS is offered, is the number local, and what registration does it trigger?
  • Can you produce the compliance position in writing for the specific destinations we sell?
Our background

The network behind the wholesale platform

A reseller buys data from someone else. What sits behind this platform is our own network infrastructure, our own billing and our own interconnect — which is what makes rate control and activation reliability possible rather than aspirational.

Hong Kong and Guangzhou operations

Our operations run across two locations: Hong Kong and Guangzhou. That gives us engineering and commercial presence in the same region as the Greater Bay Area's outbound travel market, and a Cantonese and Mandarin-speaking operation for the mainland and Hong Kong channels.

Our own 4G core and billing in Hong Kong

We operate our own 4G mobile core network and our own billing system in Hong Kong, and have been providing mobile service since the first quarter of 2016. Owning the core and the billing means usage is measured and rated by us, not reported to us by a third party.

Call centre and billing in Guangzhou

Our call centre and billing operation is established in Guangzhou. Support and settlement are handled by our own team rather than outsourced to a platform vendor, so a profile issue is resolved by the people who can actually touch the profile.

Mainland and regional interconnect

We are interconnected with China Mobile, China Unicom, China Mobile Hong Kong, Hutchison 3 Hong Kong, SmarTone Hong Kong, CITIC Telecom and China Telecom Macau. Direct interconnect is what determines both the cost per GB we can offer and how a profile behaves on the ground.

International voice and SMS termination

We carry international voice and SMS termination. That capability is what makes a voice or SMS option in selected markets a genuine product rather than a resold add-on.

Number portability across Hong Kong

We are interconnected with all Hong Kong MNOs and MVNOs for number portability — the same interconnection discipline that lets a corporate customer move lines without changing numbers, and that keeps our Hong Kong supply multi-sourced rather than dependent on a single network.

Why this matters to a distributor

Rate cards in this industry are usually a markup on somebody else's wholesale price, which means they move when that price moves. Direct interconnect, an owned core and owned billing change the shape of that conversation: rates are set from our own cost base, usage is measured at our own core, and a rate can be held for a committed volume.

Now you know what an eSIM is. Here is what it costs.

Tell us your destinations and your volumes and we will send a costed proposal, with a pilot if you want to test the network before you commit to it.