What is a prepaid SIM card and how does it work?
Whether it’s for a smartphone, a second home, or for kids, prepaid SIM cards are a flexible solution for anyone who wants full control over their mobile costs. But what exactly is a prepaid SIM card, how does it work, and how is it different from a traditional mobile plan? In this article, we’ll explain everything you need to know – clearly and with a focus on the Swiss market.
18.04.2025 | Reading time: 4 minutes
What is a prepaid SIM card?
A prepaid SIM card is a mobile phone card where you load credit first and then use this credit for calls, SMS, or data. Unlike a traditional mobile subscription, there is no monthly base fee and no contractual obligation. You only pay for what you use – ideal for anyone who wants to keep their expenses under control.
These cards work in smartphones, tablets, mobile routers, or phones for elderly people. You can use them right away once they’re registered, activated, and topped up. In many mobile provider shops, you can get your prepaid SIM card in no time – ready to use without the need for additional online verification.
How does a prepaid SIM card work?
Using a prepaid SIM card is simple: you buy the card – either online or directly in a shop – and then load the desired credit, e.g. CHF 20. You can then use this balance for calls, mobile internet, or SMS.
Many providers offer flexible prepaid bundles. These might include 500 MB of data or a flat rate for calls – valid for a day, a month, or even a year. These bundles can be activated at any time, changed flexibly, and cancelled when no longer needed.
Where can I buy a prepaid SIM card?
In Switzerland, you can buy prepaid SIM cards in:
- Electronics stores
- Supermarkets
- Kiosks and petrol stations
- Shops of mobile providers
- Online directly from the provider
The cards usually cost between CHF 0 and CHF 25 and often come with a starting credit. Registration requires an identity check, for example by uploading an ID document or via video identification.
How can I top up my prepaid credit?
There are several ways to top up your prepaid credit:
- At sales outlets like supermarkets, kiosks, petrol stations, or telecom shops
- Online using credit card, TWINT, or e-banking
- At machines (e.g. SBB ticket machines, Postomat with Postcard, ATMs with Swiss Maestro/V-Pay/M-Card)
- Through credit transfer from subscription customers of the same provider
Depending on your provider, you may enter your phone number or redeem a code. Some providers also offer automatic top-ups – for example, when your balance drops below a set amount.
What is the difference between a SIM card and a prepaid card?
"SIM card" is the technical term for the chip card that you insert into your phone. "Prepaid" refers to the billing model – in advance.
Every prepaid card is a SIM card, but not every SIM card is a prepaid card. With a mobile subscription, you pay a fixed monthly amount, often with a minimum contract period. With prepaid, you decide when and how much to pay.
Do I need a special SIM card for prepaid?
Generally, the same SIM card is used for both subscriptions and prepaid. Some providers use different SIM profiles or packaging, but technically there are very few differences.
Who is a prepaid SIM card suitable for?
Prepaid SIM cards are ideal for:
- Children and teenagers with cost control
- Light users and occasional surfers
- Tourists or expats with short-term needs
- Elderly people who appreciate simple solutions
- Secondary devices such as tablets or mobile routers
People with negative credit history also benefit, as no credit check is required.
Advantages of a prepaid SIM card
- Full cost control with no surprises
- No contract commitment – maximum flexibility
- Transparent usage – you only pay for what you need
- Ready to use immediately – no waiting time
- Ideal for kids, light users, or as a second SIM
Are there any disadvantages?
While prepaid offers many advantages, there are a few limitations:
- If you use your phone a lot (e.g. frequent streaming or calling), a subscription may be cheaper
- Multi-SIM or smartwatch options are often not available
- Convenience features like auto-renewals are not always included
Although you usually need to top up credit manually, some providers offer automatic top-ups when needed. Also note: some cards may expire if not used for a longer period – always check the provider’s usage conditions.
What happens when the credit runs out?
If your balance is used up, you can no longer make calls, send SMS, or use mobile data – unless you're connected to Wi-Fi. Usually, you’ll receive an SMS notification. If the card remains inactive for a longer period (e.g. 6–18 months), it may be deactivated.
Can I cancel a prepaid plan at any time?
There are no cancellation periods or minimum contract durations. If you stop using your prepaid SIM card, it simply expires. It’s that easy.
Do I need to activate roaming when travelling abroad?
With most providers, roaming is enabled by default. Usually, the cost limit is set to CHF 0 – you need to manually increase it to use roaming. It’s recommended to activate a suitable roaming option so you can call and browse worry-free while abroad.
How can I top up my prepaid credit abroad?
Topping up is also easy when you're abroad:
- Online via the app or website (credit card, TWINT)
- Physical top-up cards bought in advance can also be used – if you purchased them before your trip
Is prepaid available with 5G?
Yes – also with yallo. Our prepaid plans give you access to the 5G network – all you need is a 5G-compatible device and network coverage.
Looking for a simple solution with fair prices, 5G, and full control? Then check out yallo’s prepaid offers – no hidden costs and maximum flexibility.
