In most countries (US, EU, Canada, Australia), unlocking your own device is legal. However, breaking a contract with a carrier may incur early termination fees. Do not unlock for fraud (e.g., stolen devices).
Recommended stock firmware: E5577s-932_UPDATE_21.333.01.00.00.BIN (generic global version). e5577s-932 unlock file
This is the safest method. You provide the device's 15-digit IMEI number (found by dialing *#06# or checking the sticker under the battery) to the original carrier or a third-party service. In most countries (US, EU, Canada, Australia), unlocking