How do I block a call or text on my kids phone and keep them from being able to reverse it?

Instead of blocking, set communication limits

In Screen Time, you can either allow or block communication—including incoming and outgoing phone calls, FaceTime calls, and messages—from certain contacts in iCloud, either at all times or during certain periods.

1. If you haven’t already turned on Contacts in iCloud, go to Settings  > [your name] > iCloud, then turn on Contacts.
2. Go to Settings  > Screen Time, then turn on Screen Time if you haven’t already.
3. Tap Communication Limits, tap During Screen Time, then select one of the following for communication at all times (other than downtime):

• • Contacts Only: To allow communication only with your contacts.
  • Contacts & Groups with at Least One Contact: To allow one-on-one conversations only with people in your contacts and group conversations that include at least one person in your contacts.
  • Everyone: To allow conversations with anyone, including unknown numbers.

1. Tap Back at the top left, then tap During Downtime.
2. The option you selected for During Screen Time is already set here. You can change this setting to Specific Contacts, then choose one of the following:

• • Choose From My Contacts: To select contacts to allow communication with during Downtime.
  • Add New Contact: To add a person to your contacts and allow communication with that person during downtime.

If someone who’s currently blocked by your Communication Limit settings tries to call you or send you a message, their communication won’t go through.

If you try to call or send a message to someone who’s currently blocked by your Communication Limit settings, their name or number appears in red in your list of recent calls or messages, and your communication won’t go through. You can communicate with them when the communication limit is changed. If the limit applies only to downtime, you receive a Time Limit message. You can resume communication with them when downtime is over.

To resume communication with contacts who are blocked by your Communication Limit settings, change the settings by following the steps above.