Hello chukwudi177,
Thank you for reaching out in Apple Support Communities. Our recommendation is to verify that iMessage is set up on your iPhone. This will help ensure that it's activated so you can use iMessage. Here's how:
Turn on iMessage
When you communicate with others using iMessage, you can use more apps and features, like read receipts, undo send, message editing, audio messages, collaboration, inline replies, and more.
1. Go to Settings
> Messages, then turn on iMessage.
2. To select the phone numbers and email addresses you want to use with iMessage, go to Settings > Messages > Send & Receive, then choose from the available options below “You can receive iMessages to and reply from.”
Following these steps can help and is outlined here: Set up Messages on iPhone - Apple Support
We look forward to hearing back from you with an update.
Best regards.