To call anonymously in Belgium, dial #31# followed by the number you want to reach. The recipient will see "Private number" or "Unknown" instead of your real one. This works on any Belgian network, on both iPhone and Android, and it only hides your number for that single call. If you want every outgoing call to be anonymous by default, you can switch caller ID off permanently in your phone settings. Both methods are free, both are built into your phone, and neither requires a separate app. The rest of this guide walks through each option step by step, explains when each one makes sense, and covers what to do if it stops working.
The quick way: #31# before every call
This is the method most Belgians use because it's instant and reversible. You hide your number for one call without changing any settings.
Here's how it works:
Open your phone's keypad
Type #31# directly before the phone number, with no space between them
Press call as normal
For example, to anonymously call 02 123 45 67, you would dial #31#0212345678. The person on the other end sees "Private number", "Unknown", or "Withheld" depending on their phone.
The #31# prefix is a standard GSM code, which means it works on any mobile network in Belgium and across the EU. Whether you're with Proximus, Telenet, Orange, Mobile Vikings, Scarlet, or any MVNO, the code behaves the same way. There's nothing to activate and nothing extra to pay.
How to call anonymously on iPhone
If you want every call to go out without your number showing, iPhone lets you change this once and forget about it.
Open Settings
Tap Apps, then Phone (on older iOS versions, Phone sits directly in Settings)
Tap Show My Caller ID
Switch the toggle off
From that point on, every outgoing call shows up as private to the recipient. To switch it back on, follow the same path and toggle it on again.
A small note for iPhone users on certain networks: the toggle sometimes appears greyed out. This usually means the network needs to enable the feature on your line first. A quick call to your operator's customer service unlocks it.
How to call anonymously on Android (Samsung and others)
Android keeps the option in a similar place, though the wording varies slightly between manufacturers.
Open the Phone app
Tap the three-dot menu or Settings
Look for Supplementary services or Additional settings
Tap Caller ID or Show your caller ID
Select Hide number
On Samsung devices, you'll usually find it under:
Settings → Call settings → Show caller ID.
On Google Pixel, the path is:
Phone app → Settings → Calls → Additional settings → Caller ID.
When to use which method
Both methods do the same job, but the right one depends on how often you need it.
Use #31# before the number when you only want to hide your identity for one specific call. It's the fastest option and you don't have to remember to switch anything back later.
Use the phone settings when you want every call to go out privately by default. Useful for journalists, sales callers, people in sensitive roles, or anyone who simply prefers not to share their number.
There's also a third option some people don't realise exists: 31# before the number forces your caller ID to show for that single call, even if you've hidden it by default. A common mix-up is dialling #32#, which doesn't do anything on the network. If you've set your phone to always call privately but want to make an exception for one call, 31# is the code you want.
Will the person know it was me?
If you're calling someone who knows you well, they may guess. The number won't appear, but a familiar voice, time of day, or recent context can give it away. Anonymous calling hides your number, not your identity beyond that.
Some recipients also block anonymous calls automatically. If your call doesn't go through, that's likely the reason. There's no workaround on your end; the receiver has chosen not to accept calls without caller ID, and that's their right.
One important exception: emergency calls. If you dial 112 in Belgium with a hidden number, the network overrides your privacy setting automatically and shows your number to the dispatcher. This happens for safety reasons and you cannot turn it off.
What anonymous calling doesn't cover
Anonymous calling applies to voice calls only. Text messages always show your number, regardless of your caller ID settings or whether you dialled #31#. The same goes for WhatsApp, iMessage, and any other messaging app, which use their own identifiers and aren't affected by GSM codes at all.
Anonymous calling and your provider
Anonymous calling is a phone feature, not a provider feature. It works the same on Proximus, Telenet, Orange Belgium, and every MVNO operating on those networks. You don't need a special plan, an add-on, or a setting change with your operator. The phone handles it.
The only exception is the greyed-out iPhone toggle mentioned earlier, which some operators need to activate from their side. One support call solves it.
A different way to think about your phone plan
Knowing how to hide your number is a small win, but it points to something bigger. Most of us picked our current plan because it was the default, or because the process to switch mobile plans felt like too much hassle. Connectivity should work in the background, not be something you have to manage.
That's the thinking behind Firsty, the telecom operator that works for you, not against you. A global eSIM app with transparent pricing and no contracts. You can download the Firsty today and start using it on the spot with no commitment and no paperwork.
FAQ
How do I call anonymously in Belgium?
Dial #31# directly before the phone number. The recipient will see "Private number" or "Unknown" instead of your real one. This works on every Belgian network and on both iPhone and Android.
Does #31# work on Proximus, Telenet, and Orange?
Yes. #31# is a standard GSM code and works identically on all Belgian operators and MVNOs. There is no extra cost and no setting change needed with your provider.
How do I turn off anonymous calling once I've enabled it?
On iPhone, go to Settings → Apps → Phone → Show My Caller ID and switch the toggle back on. On Android, find Caller ID under your Phone app settings and select "Show number" or "Network default".
Why is the Show My Caller ID option greyed out on my iPhone?
This usually means your mobile operator needs to enable the feature on your line. Contact your provider's customer service and ask them to activate caller ID control. It's a quick fix.
Can the person I called still find out my number?
Not directly. Your number won't appear on their screen, on their bill, or in their call history. However, emergency services, the police, and certain institutions can request caller ID information through legal channels.
Does anonymous calling work when I'm abroad?
Yes. Inside the EU, the #31# code works the same way thanks to roaming rules. Outside the EU, behaviour depends on the local network, but in most countries the code is recognised.
What's the difference between #31# and 31#?
#31# hides your number for one call. 31# does the opposite: it forces your number to show for one call, even if you've set your phone to call privately by default.
Does hiding my caller ID also hide my number when I send a text?
No. The #31# code and your caller ID settings apply only to voice calls. Text messages always show your number to the recipient.
Will anonymous calls show on my bill? Yes, on your own bill.
The call appears as normal in your usage history. Anonymous calling only hides your number from the recipient, not from your operator.
Take back control of your phone setup
Hiding your number is a small thing you didn't know you could control. There's a lot more about your telecom setup in the same category. Download the Firsty app to experience a different way of doing telecom: transparent, fair, and built around you.
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