When a country decides to replace old banknotes with new ones, they typically implement a phased approach to withdraw the old notes from circulation while introducing the new ones. Here's how it generally works:

1. Announcement: The central bank or relevant authority announces the issuance of new banknotes and provides information on their design, security features, and timeline for introduction.

2. Introduction of New Banknotes: The new banknotes are gradually introduced into circulation through banks, financial institutions, and ATMs. People start using the new notes alongside the old ones.

3. Dual Circulation Period: During a transition period, both the old and new banknotes are accepted as legal tender. This period allows people to become familiar with the new notes and gives them time to exchange their old notes for new ones.

4. Withdrawal of Old Banknotes: As the transition progresses, the central bank begins to gradually withdraw the old banknotes from circulation. They may set deadlines for the public to exchange old notes for new ones at banks or through other designated channels.

5. Exchange Period: The central bank usually provides a window of time, often several months to a year or more, during which people can exchange their old banknotes for new ones at banks, post offices, or other authorized locations.

6. Ceasing Legal Tender Status: After the exchange period ends, the old banknotes cease to be legal tender. They may no longer be accepted for transactions at businesses, although some central banks may continue to exchange old notes for a limited time.

7. Redemption Period: In some cases, there may be a redemption period during which individuals can still exchange old banknotes for new ones, typically through the central bank or designated agencies. After this period, the old notes may lose their value entirely.

The specific process and timelines may vary depending on the country and the central bank's policies. However, the goal is to ensure a smooth transition from old to new banknotes while minimizing disruptions to the economy and public confidence in the currency.