Before you start

Passport for a prepaid SIM
Personal identity code and a Finnish payment method for a contract
An unlocked or eSIM-capable handset
An identity check, for the mobile certificate

Step-by-step

1
Buy a prepaid SIM on arrival
Available in supermarkets, R-kioski and operator shops, active immediately. Finnish prepaid plans commonly include large or unlimited data at very low prices, so this is not a stopgap so much as a perfectly reasonable long-term option.
In personWho: YouDay 1
2
Move to a contract once you have an identity code
Postpaid plans run a credit check against the identity code. Unlimited-data plans are the norm and the differentiator between operators is speed tier rather than allowance.
OnlineWho: YouMonth 1
3
Ask about the mobile certificate
Finnish operators can activate a mobiilivarmenne on your SIM after an identity check. It functions as strong electronic identification for Suomi.fi and many other services, independently of any bank. It is genuinely useful and almost never mentioned to newcomers.
In personWho: You
4
Check what the housing company already provides
Finnish taloyhtiöt frequently include a broadband connection in the monthly maintenance charge (hoitovastike), and the tenant inherits it. Ordering a separate line on top is a common duplication. Ask the landlord or the housing company.
Via employerWho: Your landlord or housing company
5
Keep your number when switching
Porting is fast and free in Finland and handled by the new operator. Never cancel the old subscription first.
OnlineWho: You
6
Use the SIM abroad without worrying inside the EEA
EU roam-like-at-home covers the EEA, so a Finnish plan works at domestic rates in Sweden, Denmark, Norway and Iceland. Unlimited domestic data is subject to a fair-use cap when roaming, which is the one place the Finnish 'unlimited' has a limit.
Mobile appWho: You

Documents you’ll need

Passport for prepaid
Personal identity code for a contract
Finnish bank details
Address confirmation, for fixed broadband

Things most newcomers don’t know

Your SIM can be a legal identity here, which is unusual anywhere.

The mobiilivarmenne is a certificate issued by Finnish mobile operators, tied to your SIM and activated after an identity check, that constitutes strong electronic identification under Finnish law. It authenticates to Suomi.fi and therefore to the tax administration, Kela and municipal services — without needing a bank. For a newcomer waiting on a bank appointment, this is the single most useful workaround available, and it is essentially never mentioned in relocation advice.

Source: Traficom / Suomi.fi

Unlimited data is the default, not the premium tier.

Finland's mobile market settled on unlimited-data plans differentiated by speed rather than by allowance, and Finnish subscribers consequently use more mobile data per head than almost anyone. The practical effect for a newcomer is that tethering a laptop, streaming on the commute and treating mobile data as a home broadband substitute are all normal here and cost nothing extra — which changes how you think about needing a fixed line at all in a temporary flat.

Source: Traficom

The housing company may already be paying for your broadband.

Finnish taloyhtiöt often negotiate a collective broadband contract and bill it inside the monthly maintenance charge, which the landlord passes on in the rent. Because it never appears as a separate invoice, tenants routinely order their own connection and pay twice for a year before noticing. Ask the landlord what the hoitovastike includes before ordering anything.

Source: community-reported

'Unlimited' has a fair-use limit the moment you cross a border.

EU roam-like-at-home lets you use a Finnish plan at domestic rates across the EEA, but operators may apply a fair-use policy to genuinely unlimited domestic data when roaming, capping the volume at domestic prices. For a weekend in Stockholm it is irrelevant; for someone spending months working from another EEA country it is not, and it is the one asterisk on Finland's otherwise remarkable mobile deal.

Source: Traficom

Common mistakes to avoid

Paying for broadband already covered by the housing company's maintenance charge.
Not asking about the mobile certificate while waiting weeks for bank credentials.
Cancelling an old subscription before the number is ported.
Assuming unlimited data stays unlimited while roaming for extended periods.
Changing operator and losing an active mobile certificate without reissuing it.

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