To set a caller tune on Airtel, you can follow these steps:

1. Call the Airtel Caller Tune Number: Dial 543211 from your Airtel mobile number.
2. Browse and Select Caller Tunes: Listen to the instructions and follow the prompts to browse through the available caller tunes. You can choose from various categories or search for specific songs or artists.
3. Select the Caller Tune: When you hear a caller tune that you like, follow the instructions to select it as your caller tune.
4. Confirm your Selection: Once you have made your selection, you will be prompted to confirm it. Follow the instructions to confirm and activate the caller tune.
5. Set the Caller Tune as Default or for Specific Contacts (optional): You can choose to set the caller tune as the default for all incoming calls or assign it to specific contacts. Follow the instructions to make your preferred selection.
6. Confirmation Message: After completing the process, you will receive a confirmation message indicating that your caller tune has been set successfully.

Alternatively, you can also set a caller tune through the Airtel Thanks app or the Airtel website. Here's how:

Airtel Thanks App:

1. Download and install the Airtel Thanks app from the App Store or Google Play Store.
2. Open the app and log in with your Airtel mobile number.
3. Navigate to the "Hello Tunes" or "Caller Tunes" section within the app.
4. Browse through the available caller tunes and select the one you want.
5. Follow the instructions to confirm and activate the caller tune.

Airtel Website:

1. Visit the Airtel website (www.airtel.in) on your web browser.
2. Log in to your Airtel account using your mobile number and OTP (One-Time Password) verification.
3. Look for the "Caller Tunes" or "Hello Tunes" section on the website.
4. Browse through the available caller tunes and select the one you want.
5. Follow the instructions to confirm and activate the caller tune.

Please note that there may be charges associated with setting and maintaining caller tunes, depending on the specific Airtel service plans and offers available to you. It's advisable to check the pricing and terms of service with Airtel or consult their customer support for any specific inquiries or assistance.