Before you start

Passport or eID for SIM registration
A Belgian address, for fixed broadband
A Belgian bank account for direct debit on most postpaid plans
An unlocked or eSIM-capable handset

Step-by-step

1
Buy a prepaid SIM on day one and register it
Prepaid SIMs are sold in supermarkets and phone shops and work immediately, but must be registered with identification under the 2017 anti-terrorism rules. Registration is quick and can usually be done in the shop or online. An unregistered SIM stops working.
In personWho: YouDay 1
2
Compare the smaller operators before signing anything
Mobile Vikings, hey!, Scarlet and similar operate on the major networks at markedly lower prices. Coverage is the same infrastructure. The big three's headline bundles are worth it mainly when you want mobile and fixed from one provider.
OnlineWho: You
3
Use the BIPT price comparison tool
The federal telecoms regulator runs an independent comparison of mobile and fixed bundles. It is the only neutral source in a market where every other comparison site takes commission, and it exists precisely because Belgian telecom pricing is hard to read.
OnlineWho: You
4
Check what your building is actually connected to
Brussels has a mix: copper and fibre from Proximus, coax from Telenet/VOO depending on the street, and fibre rollout that is street-by-street rather than uniform. Ask the landlord or the agent what is installed and whether there is an existing connection point, before you sign, if your work depends on the line.
OnlineWho: You
5
Switch using Easy Switch rather than cancelling
Belgium's Easy Switch procedure makes the new operator handle the migration, keeping your number and avoiding a gap in service. Cancelling the old contract yourself first is the classic error and leaves you disconnected.
OnlineWho: You
6
Expect a technician appointment for fixed lines
Installation slots for fixed internet run one to three weeks out and often need someone at home. If you work remotely, arrange a mobile data fallback for the first month rather than assuming the line will be live on move-in day.
OnlineWho: You1–3 weeks

Documents you’ll need

Passport or eID for SIM registration
Proof of address for fixed-line installation
Belgian bank account details for direct debit
Lease or landlord permission, if cabling work is needed

Things most newcomers don’t know

There is no anonymous prepaid SIM in Belgium, and an unregistered one dies.

Since 2017 every prepaid card must be linked to an identified holder. You can buy the SIM before you have an eID by registering with a passport, but you cannot skip registration — the card is deactivated. Travellers who bought a Belgian SIM years ago and expect the same casual purchase are surprised, and people who buy one for a family member and never register it lose the credit.

Source: BIPT

The small operators run on the same towers for substantially less.

Mobile Vikings, hey!, Scarlet and others resell capacity on the Proximus, Orange and Telenet networks. Coverage and speed are the infrastructure's, not the brand's. Belgian mobile pricing has been criticised for years as high by EU standards, and the gap between a flagship bundle and a reseller plan with the same coverage is large enough to be worth an hour of comparison.

Source: BIPT

You can leave a Belgian telecom contract after six months without penalty.

Consumer protection rules let residential customers terminate mobile and internet contracts at any time once six months have passed, without early-termination charges. This is unusually generous and it changes the calculus at signing: there is little reason to accept a long commitment for a discount, and it makes trying an operator low-risk. Providers do not advertise it.

Source: BIPT

Fibre in Brussels is street-by-street, not citywide.

Rollout is progressing but uneven, and a building on a fibred street may still be served by copper or coax internally. The listing will say 'high-speed internet available' either way. If your income depends on the connection, ask what is physically installed in the building and whether there is an existing termination point in the flat, before signing the lease.

Source: community-reported

Common mistakes to avoid

Buying a prepaid SIM and never completing the mandatory registration.
Signing a flagship bundle without comparing the resellers on the same network.
Cancelling the old contract yourself instead of using Easy Switch, and losing the number.
Assuming fibre because the street has it, without checking the building.
Accepting a long commitment when Belgian rules let you leave after six months anyway.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.