iMessage is not working after activating eSIM

Hi vennila288,

Please check out this link, and ensure the correct process was used to set up eSIM, and that all of the requirements have been met, so we can make sure there aren't any issues there: About eSIM on iPhone

Use eSIM Carrier Activation on iPhone

Some carriers and worldwide service providers can assign a new eSIM to your iPhone, making setup easy. This usually happens when you purchase a carrier-connected iPhone from Apple in the United States or from a carrier and you provide your cellular-plan details. If an eSIM was assigned to your iPhone when you bought it, turn on your iPhone and follow the instructions to activate your eSIM. 

If you're switching to iPhone (from an Android phone, for example), contact your carrier to transfer your phone number to your iPhone through eSIM Carrier Activation or by scanning a QR code from your carrier.

If you contacted your carrier for an eSIM after you set up your iPhone, and they set up eSIM Carrier Activation, follow these steps: 

1. Verify that both devices are signed in with the same Apple ID, the devices are unlocked, nearby with Bluetooth enabled, and using iOS 16 or later.

2. When a notification appears that says Carrier Cellular Plan Ready to Be Installed, tap it.

3. In the Settings app, tap Carrier Cellular Plan Ready to Be Installed.

4. Tap Continue, at the bottom of the screen.

5. Make a call on your iPhone to check its cellular connectivity. If you can't make a call, contact your carrier.

6. If the plan you activated replaces the plan on your physical SIM, remove your physical SIM. Then restart your iPhone.

If you're still unable to enable iMessage, please check out this link, which has some additional information and suggestions that can help resolve iMessage and FaceTime issues: If you can’t turn on or sign in to iMessage or FaceTime on your iPhone

Thanks!