Airtel postpaid e-sim messages not able to send and receive

Thanks for posting in the Apple Support Communities yashpal241,

If you're having issues with Messages, the following steps may help:

If you see a red exclamation point

If you try to send a message and you see  with an alert that says Not Delivered, follow these steps:

1: Check your network connection.

2: Tap , then tap Try Again.

3: If you still can’t send the message, tap , then tap Send as Text Message. Messaging rates may apply. Contact your carrier for more information.

You can find these steps along with additional information that may be useful, here: If you can't send or receive messages on your iPhone or iPad

Cheers!