Before you start

An unlocked or eSIM-capable handset
Passport for SIM registration
PESEL, a Polish address and a bank account for a postpaid contract
Landlord or building administrator consent for a fixed-line installation

Step-by-step

1
Buy and register a prepaid SIM
Available in operator shops, kiosks and supermarkets. Polish law requires every SIM to be tied to an identified person, so registration happens against your passport at the point of sale. An unregistered SIM is deactivated.
In personWho: YouPLN 5–30 including starter credit
2
Do nothing urgently if you arrive from another EU country
Roam-like-at-home means your existing EU SIM works at domestic rates. Use the breathing room to compare rather than buying at the airport.
OnlineWho: You
3
Ask about internet before you sign the lease
In Stare Miasto and Kazimierz, ask the landlord or administrator which operators are actually connected to the building, not which advertise the postcode. Conservation rules on facades and stairwells restrict new cabling, and some tenements have only coax or copper.
In personWho: YouBefore signing
4
Consider fixed wireless instead of waiting
5G coverage across Kraków is strong and unlimited-data mobile plans are cheap. A router on a mobile plan is a legitimate primary connection here and it removes any dependency on a landlord, an administrator and a conservator all agreeing.
OnlineWho: You
5
Move to postpaid once you are settled
Contracts want PESEL, a Polish address and a bank account for direct debit. Prepaid pricing is good enough that plenty of long-term residents never bother switching.
In personWho: You

Documents you’ll need

Passport for SIM registration
PESEL and Polish bank account, for postpaid
Lease or landlord consent, for a fixed-line installation
Proof of address, for some contracts

Things most newcomers don’t know

Fibre in the old town and Kazimierz is a building question, not a postcode question.

Kraków's historic core is a conservation area and the tenements inside it are individually protected. Running new cabling across a listed facade or through a protected stairwell needs consents that operators will often not pursue for a single flat. Coverage checkers report the street as served while your specific building is not, and the gap only appears after you have signed.

Source: community-reported, consistent with Kraków conservation rules

Anonymous prepaid does not exist in Poland.

Every SIM, including pay-as-you-go, must be registered against an identified person under Polish telecommunications law. There is no unregistered option to buy and one sold without proper registration simply stops working within days. Bring your passport to the kiosk rather than expecting to hand over cash.

Source: Polish telecommunications law

A mobile router is a serious answer here, not a stopgap.

Polish mobile data is among the cheapest in the EU, 5G coverage across Kraków is dense, and unlimited plans are widely sold. For a flat where fibre is blocked by the building, that is the difference between working from home in week one and negotiating with a heritage conservator for a month. Plenty of people in the centre run this permanently.

Source: community-reported

Number portability is free and the old contract must not be cancelled first.

Poland has straightforward mobile number portability and switching between operators takes a day or two. The failure mode is cancelling the outgoing contract before initiating the transfer, at which point the number is released and no longer yours to move. Start the port from the new operator and let them terminate the old one.

Source: UKE — Office of Electronic Communications

Common mistakes to avoid

Signing a lease in the old town without asking which operators reach the building.
Expecting to buy an anonymous prepaid SIM.
Paying airport roaming prices when EU roam-like-at-home already covers you.
Cancelling an old contract before starting the number transfer.
Committing to a 24-month contract before you have PESEL and a Polish bank account.

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