Key Points:
- SIM cards have gotten smaller over the years, with the most popular physical, removable Subscriber Identity Module being Nano.
- Most modern phones (from 2017 and onwards) natively feature eSIM support, meaning there's no longer a need for a physical SIM card when you can do it all from software.
- Talkmobile's SIM-only plans feature a choice of either physical SIM cards or eSIMs, depending on your smartphone's compatibility, so you'll have the choice if you need it.
A Subscriber Identity Module (or SIM card) stores important identifying data, such as your phone number and service provider, allowing you to use mobile data, make/receive calls, and send/receive text messages. They can come in a variety of different sizes. However, in 2026, virtual eSIMs (Electronic Subscriber Identity Modules) are becoming more popular than ever. We're going over everything you need to know about what SIM cards are and how they work.
What does a SIM card do?
A SIM card is a removable piece of plastic that contains important data that connects your smartphone with your provider's network. It has a unique ID, which acts as a form of authentication and verification for your phone number, and the complete use of your phone's services when connected to a network. They don't hold much data, only typically around 32 to 128KB; however, they're incredibly important.
SIM card sizes explained in 2026
| SIM size | Description | Dimensions | Introduction Year |
| Standard | Developed in 1991 and used in old mobile phones. | 85 mm x 53.98 mm | 1991 |
|---|---|---|---|
| Mini | Replaced the larger SIMs, phased out by the late 2000s. | 25 mm × 15 mm | 1996 |
| Micro | Replaced Mini SIM as the more popular alternative. | 15 mm x 12 mm | 2010 |
| Nano | Most common SIM for phones without eSIM support. | 12.3 mm x 8.8 mm | 2012 |
| eSIM | Embedded into device PCB; non-removable. | ~5 mm × 6 mm (or less) | 2017 |
SIM cards have massively evolved over the last 30 years. They've gotten smaller as phones have become more advanced. Since the mid-2010s, Soldered eSims have risen in popularity. If you've bought a phone in the last five to 10 years, there's a high chance it will feature eSIM compatibility; it's common nowadays on the latest iPhones, Samsung Galaxy handsets, Google Pixels, and many popular flagship, mid-range, and modern budget offerings.
With that said, eSims are not entirely standardized everywhere in the world. It's entirely common for cheaper/entry-level handsets to not feature any form of eSIM compatibility. As such, you may be provided with a micro or nano-SIM physical SIM card instead of it being baked onto your handset's motherboard; eSIMs are typically 6mm x 5mm, but iSIMs (a kind of next-generation electronic SIM card) can be as small as 1mm². Regardless of delivery method (physical size), the functionality is the same: as smartphones got sleeker, SIM cards got smaller, until today, where they're (almost always) included within the hardware itself and are non-removable.
Which SIM card is best for SIM-Only plans in 2026?
Talkmobile's SIM-Only plans include the option of both a physical SIM card and an eSIM, provided you have a handset that's compatible. A physical SIM card will be Nano-sized, the smallest and most-used in 2026, whereas an eSIM can be activated as soon as the plans are put through. Plans can be configured from either 30-day or 12 months, and give you unlimited calls and texts as well as a fixed amount of mobile data ranging from 15GB to 200GB a month.
You can check whether your phone has an eSIM by dialling *#06# on your keypad. Alternatively, you can check the settings menu on your iOS device under Settings > Mobile Data and Android with SIM Manager.
