> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hologram.io/llms.txt
> Use this file to discover all available pages before exploring further.

# IMEISV vs IMEI

> Understand the difference between IMEI and IMEISV and how they appear in Hologram.

The **[IMEI](https://en.wikipedia.org/wiki/International_Mobile_Equipment_Identity)** is the device's modem identifier. The value Hologram stores and shows is the one we receive from the cellular network each time a device connects successfully.

The Hologram REST API also returns the **IMEISV**. The difference is in the final digits:

* **IMEI** — 14 digits plus a 1-digit checksum.
* **IMEISV** — the same 14 digits plus a 2-digit **software version** instead of the checksum.

The software version lets you distinguish module firmware versions across devices that use the same cellular module.

#### Traditional IMEI = IMEI + 1 digit checksum

**4** **9** **0** **1** **5** **4** **2** **0** **3** **2** **3** **7** **5** **1** *8*

#### IMEISV = IMEI + 2 digit software version

**4** **9** **0** **1** **5** **4** **2** **0** **3** **2** **3** **7** **5** **1** *0* *1*