If you want to stop receiving messages from unknown numbers on your iPhone, you can follow these simple steps:

1. Open the Settings app on your iPhone.
2. Select Messages.
3. Scroll down and select “Unknown & Spam” under Message Filtering.
4. Enable “Filter Unknown Senders” on the next screen.

By enabling this feature, iMessage will filter out texts from numbers that are not saved in your address book. However, it’s worth noting that it may also classify texts from people you know but are not on your contact list as unknown. To avoid missing any important messages, make sure to save the contact details of everyone you know. If you can’t find a message, you can check the Unknown Senders folder by following these steps:

1. Open the Messages app.
2. Tap Filters at the top right.
3. Select Unknown Senders.
4. Scroll down to see if the text landed there.

If you receive a message from someone you know that includes a link you can’t open, you can make the link work by replying to the message. After replying to an SMS or MMS message three times or adding the number to your contacts, iOS will stop filtering out messages from that particular sender. Instead, their texts will show up in your primary inbox.