# What is multi-IMSI? Identities on one SIM

Multi-IMSI puts several subscriber identities on one SIM and selects among them by country or network. It lets a device present a local identity in each market without changing the card. It does not by itself give the end customer a local subscription, remove registration or admission rules, or create the roaming or wholesale arrangement behind the identity.

- Multi-IMSI selects among several IMSIs on one SIM; only one identity is active at a time.

- A local-looking IMSI does not by itself give the end customer a local subscription: the commercial arrangement, registration and roaming rules still apply.

- A switch re-registers the device on the network, so the data session is rebuilt.

- Multi-IMSI is a SIM application behavior, not a single 3GPP service; implementations differ by provider.

## Several identities, one subscription at a time

A multi-IMSI SIM holds several IMSIs and an application that chooses which one to present. The device attaches to the network with one identity at a time. When the SIM switches, the network authenticates the new IMSI and the subscription behind it applies. That is the whole trick: the card does not move, but the identity the network sees does.
The commercial arrangement behind each IMSI is separate, and there are two common cases. A sponsor IMSI from another country reaches the local network as a roamer, under a roaming agreement the provider already holds. Or the provider holds a local range wholesale from an operator in the market; the network then sees a local subscriber. In that second case, the end customer's contract, the registration of the line and the permanent-roaming position are still separate questions. Neither case turns the card into a local subscription for the customer by itself. Registration, admission and roaming rules still apply to the device and to the traffic.

### One card, several IMSIs

The switch changes the identity on the card; the device and the radio path stay the same.

Alt: Four layers labeled device, eUICC, roaming identity and subscription. The identity layer shows IMSI 1 in the first state and IMSI 2 in the second.

State A presents IMSI 1 and state B presents IMSI 2. The device, the eUICC and the subscription layer stay in place; only the identity changes. The network authenticates the selected IMSI, so the device re-registers and the data session is rebuilt under that identity.

| Item | Value | Note |
| --- | --- | --- |
| IMSI 1 active · 1 | Device |  |
| IMSI 1 active · 2 | eUICC |  |
| IMSI 1 active · 3 | Roaming identity | IMSI 1 |
| IMSI 1 active · 4 | Subscription |  |
| IMSI 2 active · 1 | Device |  |
| IMSI 2 active · 2 | eUICC |  |
| IMSI 2 active · 3 | Roaming identity | IMSI 2 |
| IMSI 2 active · 4 | Subscription |  |

Source: ITU-T E.212 (06/2024): hierarchical identification of areas, networks and subscriptions (https://www.itu.int/dms_pubrec/itu-t/rec/e/T-REC-E.212-202406-I!!SUM-HTM-E.htm)

## How selection works in public terms

The SIM application chooses the identity. The policy can follow the country, the visited network or a rule the provider loads onto the card. A switch can start when the device detects a new network, when a timer expires or when the platform sends a command. The device then detaches, re-registers with the new IMSI and rebuilds its data session.
The details differ by provider. The number of identities, the selection order, the time to switch, the fallback when no identity is valid and the way a switch is triggered are not standardized as one service. Multi-IMSI is a SIM application behavior, not a single 3GPP specification. Ask for the market list, the selection policy and the test evidence rather than assuming the label means a specific capability.

## Local-looking is not the same as local

An IMSI whose country and network codes fit the market looks local to the network: it is a local subscriber, not a roamer. That still does not make it a local subscription for the end customer. The provider may hold the range wholesale from a local operator, and the customer's contract, the line registration and the permanent-roaming position remain separate questions. A sponsor IMSI from another country is the other common model: the network authenticates it as a roamer under a roaming agreement. The table below separates the local-range case from a local subscription.

### A local-looking identity is not a local subscription

| Question | A local-looking identity (local range) | A local subscription |
| --- | --- | --- |
| Who holds the identity | The provider, under a wholesale arrangement with a local operator | The operator in that market, under the customer's contract |
| What the network sees | A local subscriber under the provider's range | A local subscriber under the customer's contract |
| What changes at the border | The SIM selects another IMSI and re-registers | Nothing; the subscription already belongs there |
| What it does not remove | Registration, admission and roaming rules | Registration, admission and roaming rules |
| What happens when it fails | The SIM falls back to another identity or loses service | The local contract and the number follow local rules |

Country and network codes are defined in ITU-T E.212. A sponsor IMSI from another country is a third case: the network authenticates it as a roamer under a roaming agreement. A code that fits a market is not a license to operate there.

## What it does not solve

It does not remove registration, identity checks or admission rules. A local-looking IMSI does not exempt a device from line registration, and it does not make a foreign entity local. It does not create coverage: if the destination operator does not run the band or the network, the identity does not help. It does not create the roaming or wholesale agreement behind the identity, because that commercial relationship still has to exist. And it does not solve permanent roaming, because a subscription that stays in one country too long can attract scrutiny whatever identity it presents.
It also does not change the MSISDN by itself. The IMSI identifies the subscription and the MSISDN is the diallable number. A switch can come with a new number, an existing number or no number at all, depending on the arrangement. If the application depends on a stable number for replies, ask how the number is managed across switches.

## How long a switch takes

A switch is a re-registration, not a settings change. The device detaches, the SIM presents the next identity, the network authenticates it and the data session is rebuilt. That can take seconds or longer, depending on the network and the device. A failed switch can leave the device without a usable identity until the next attempt or a fallback.
Design for the gap. If the application cannot tolerate a re-registration, buffer the data and retry when the session returns. Log the identity in use and the time of the switch, so a support ticket can tell which subscription was active. Test the switch on the real device and firmware, including a failed switch and a fallback.

### What to check before you buy

- [ ] The market and network list behind the identities, with the date it was checked.
- [ ] How a switch is triggered, who controls the policy and what happens when it fails.
- [ ] Whether the device or module needs a specific SIM form or firmware support.
- [ ] Which MSISDN the customer sees, and whether it survives a switch.
- [ ] How the active identity is reported, and whether the platform exposes it.
- [ ] Who owns the identities, and what the exit terms are.

Ask for a test in each launch market, on the real device, with the real firmware.

### Check what you learned

**Multi-IMSI can present a local-range IMSI in Brazil or a sponsor IMSI from abroad. Is either one a Brazilian subscription for the customer?**

Not automatically. A sponsor IMSI is authenticated as a roamer under a roaming agreement. A Brazilian range held wholesale is seen as a local subscriber, but the customer's contract, the line registration and the permanent-roaming position are separate questions.

**What happens to the data session when the SIM switches identity?**

The device detaches, re-registers with the new IMSI and rebuilds the data session. The application may see a gap.

**Does multi-IMSI remove the need for a roaming agreement?**

No. It changes which identity is presented. The commercial relationship behind that identity still has to exist.

## FAQ

**Does multi-IMSI avoid roaming agreements?**

No. It changes which identity is presented, not the commercial or regulatory reality underneath.

**Does it change my phone number?**

Not by itself. The IMSI and the MSISDN are separate. Ask which number the user sees and whether it changes on a switch.

**Can I see which IMSI is active?**

Usually through the SIM toolkit, an over-the-air command or the provider's platform. Ask before you buy, because the answer affects support.

**Does multi-IMSI work on any SIM?**

No. The SIM needs the application and the provider's identities. A standard SIM without the applet cannot switch.

**Multi-IMSI or eUICC?**

Multi-IMSI suits cross-border movers that need local-looking identity with simple logistics. eUICC suits long-lived fleets that need remote profile management. The [comparison](/en/resources/learn/multi-imsi-vs-euicc/) covers the trade-offs.

## Sources

- [ITU-T E.212 (06/2024): the international identification plan for public networks and subscriptions](https://www.itu.int/dms_pubrec/itu-t/rec/e/T-REC-E.212-202406-I!!SUM-HTM-E.htm) — Accessed: 2026-10-19
- [3GPP TS 23.003: numbering, addressing and identification](https://www.3gpp.org/ftp/Specs/archive/23_series/23.003/) — Accessed: 2026-10-19
- [GSMA SGP.22 v3.0: consumer remote provisioning, for the profile and identity model](https://www.gsma.com/solutions-and-impact/technologies/esim/gsma_resources/sgp-22-v3-0/) — Accessed: 2026-10-19
- [GSMA SGP.32 v1.2: IoT remote provisioning and management](https://www.gsma.com/solutions-and-impact/technologies/esim/gsma_resources/sgp-32-v1-2/) — Accessed: 2026-10-19

Updated: 2026-10-19