> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://help.surfroam.com/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# What is IMSI?


### **What is IMSI?**

An international mobile subscriber identity ( **IMSI**) is a unique identifier mobile networks use to recognize a subscriber. In the case of **Surfroam**, IMSI refers to different mobile network profiles stored within a **Surfroam eSIM or SIM**.

### **How Surfroam Uses IMSI**

Surfroam is designed for **frequent travelers** and includes a **multi-layered backup system** to ensure connectivity in every covered country.

* **Surfroam eSIM** carries multiple IMSI profiles: **IMSI 2, IMSI 7, IMSI 10, IMSI 22, IMSI 25, and IMSI 26**.
* **Surfroam SIM** includes **IMSI 2, IMSI 10, IMSI 22, and IMSI 23**.

### **How IMSI Works in Different Countries**

* The **eSIM automatically selects** the best IMSI in each country and applies the correct **APN** settings.
* If needed, you can **manually switch the IMSI** for better connectivity.

**Example:**  
In **Portugal**, Surfroam provides coverage via **IMSI 7, IMSI 22, IMSI 23, and IMSI 25**. If one IMSI does not work, you can switch to another for a stable connection.

### **Best Device for Surfroam**

From our experience, **iPhones with eSIM** offer the best performance as they:  
✔ Automatically switch between IMSIs in most countries.  
✔ Provide easy manual management if needed.

To ensure a seamless travel experience, it’s essential to **understand how to switch IMSI profiles and set the APN manually** when necessary.