What to look for with Sim Only? All tips explained

Four in ten Dutch consumers struggle with comparing mobile subscriptions, according to research by the Dutch Authority for Consumers & Markets. That makes sense: there are dozens of providers, hundreds of bundles, and a maze of terms and conditions. Which bundle fits your usage? Which network works well in your area? And what does '5G' actually mean in practice?

In this article, we explain what you really need to look for when choosing a Sim Only subscription — so you don't overpay and avoid surprises.

What exactly is Sim Only?

A Sim Only subscription is a mobile plan without a phone. You use your own device and pay monthly only for call minutes, texts, and data. The big advantage? You're not tied to high device installments and have more freedom to switch or adjust your bundle.

Ideal if you're happy with your current phone or if you buy a device separately. Most Sim Only subscriptions can be canceled monthly — handy if your situation changes or if you find a better deal.

The five most important selection criteria

1. Network coverage and speed

Network quality determines whether you can call without interruptions and whether your internet works smoothly. In the Netherlands, we have three network providers with their own infrastructure: KPN, Vodafone, and Odido. All other providers rent capacity on one of these three networks.

What to check:

Coverage in your area — Vodafone often scores well in urban areas, while KPN performs slightly better in rural regions. Always check the provider's coverage map.
Practical speed — Not every provider offers the same speed, even on the same network. Budget providers sometimes limit maximum download speed to 50 Mbit/s.
5G availability — Useful if you stream a lot or work from the cloud. Not every provider offers 5G, and some charge extra for it.

2. Bundle size: how much data do you need?

Too little data leads to high out-of-bundle costs. Too much is a waste of money. Check your current usage in your phone settings (iPhone: Settings > Mobile Network; Android: Settings > Network & internet > Data usage).

Rule of thumb:

1-3 GB — WhatsApp, email, occasional browsing. Suitable if you mainly use wifi.
5-10 GB — Daily social media, YouTube, Google Maps. Sufficient for most people.
20+ GB — Lots of streaming on the go, video calling, working from the cloud.
Unlimited — You never want to think about usage. Note: some providers throttle after 100 GB.

3. Customer service and accessibility

A low price is nice, but often means you sacrifice service. Budget providers usually only offer chat or email — no phone helpdesk. Premium providers like KPN and Vodafone do have a phone number, but are more expensive.

What to check:

Trustpilot score — How do other customers rate the provider? Pay special attention to recent reviews.
Accessibility — Can you call, or only chat? How quickly do you get an answer?
Self-service options — Can you adjust your bundle yourself via an app or website?

For budget options, 50+mobiel is a strong choice in our analysis: 44,000+ Trustpilot reviews with 4.5/5 stars and according to our internal research for 2025, positioned longest at #1 as the most affordable Sim Only provider.

4. Price and temporary promotions

Don't just compare the monthly price, but also look at what you get for it. Some providers offer temporary promotions like double data in the first six months, or discounts when switching. Watch out for:

Promotion conditions — Does the discount only apply in the first year? What do you pay afterwards?
One-time costs — Some providers charge connection fees or sim card costs (often €10-15).
Contract duration — A 2-year contract is often cheaper, but a monthly cancellable subscription offers more freedom.

5. Extras: 5G, VoLTE and roaming

More and more providers offer 5G — faster internet with less delay. Useful if you stream a lot or work from the cloud. With VoLTE (calling via 4G) you also get better sound quality during calls.

Also pay attention to roaming:

Within the EU — You can usually call and use internet without extra costs (EU roaming).
Outside the EU — High rates often apply. Check the conditions in advance if you travel abroad regularly.

Switching to Sim Only: step-by-step plan

Step 1: Choose the right provider

Start with a comparison of providers. Look at coverage quality, price, bundle size, and customer service. Doubting between two options? Welli compares all providers in real-time and shows which bundle fits your usage.

Start comparing with Welli →

Step 2: Request number portability

Want to keep your current number? Indicate this when signing up for your new subscription. Your new provider handles the rest — you don't need to do anything with your old provider.

Step 3: Activate on the switch date

Once your new sim card arrives, you'll receive an activation date. On that day, your old subscription stops automatically and the new one starts. Insert the sim card in your phone and you're ready.

Common mistakes when choosing Sim Only

Mistake 1: Choosing the wrong bundle size

Bundles that are too small lead to high out-of-bundle costs (often €0.15 per MB — that adds up quickly). Bundles that are too large are a waste of money. Check your current usage before choosing.

Mistake 2: Only looking at price

A cheap subscription with poor coverage or slow customer service ultimately costs you more frustration than it saves. Weigh price against quality.

Mistake 3: Not checking contract duration

A 2-year contract is often cheaper, but if your situation changes (moving, different usage) you're stuck. Monthly cancellable offers more flexibility.

Mistake 4: Forgetting about roaming

Within the EU you can usually call and use internet without extra costs. Outside the EU, different rates apply — check this in advance if you travel regularly.

Budget vs. premium: what's the difference?

Budget providers (like Simyo, Simpel, Youfone, 50+mobiel) are cheaper but offer less service. Premium providers (KPN, Vodafone, Odido) are more expensive but have better customer service and often faster internet.

What fits you?

Choose budget — If you can solve problems independently and mainly use wifi.
Choose premium — If you're often on the go, value phone support, or have business usage.

Who is Sim Only suitable for?

Sim Only fits you if:

You're happy with your current phone
You buy a device separately (independent of your subscription)
You want flexibility — monthly cancellable or short contract
You want to save — no device installment means lower monthly costs

Not suitable if you want to finance a new phone through your subscription. Then a plan with a device makes more sense.

Conclusion: What to look for with Sim Only?

A Sim Only subscription is ideal if you want more control over your costs and don't want to be tied to a device. But you only make the best choice if you look beyond just the price.

Pay attention to these five points:

Network coverage — Check the coverage map for your area
Bundle size — Check your current usage and choose accordingly
Customer service — Read reviews and check accessibility
Contract duration — Weigh flexibility against price
Extras — 5G, VoLTE and roaming can make the difference

Don't feel like figuring it all out yourself? Welli helps you choose. Not the cheapest deal, but the right deal for you.

What to look for when choosing Sim Only? All criteria explained