SMS blocking restrictions aren’t working

Environment

• Knox Service Plugin

Overview

Devices that have blocked phone numbers using SMS control policies are still able to send and receive SMS messages from phone numbers they’ve blocked.

Cause

By default, devices with Samsung messages and Google messages use Rich Communication Services (RCS), instead of SMS. As a result, SMS blocking policies won’t work. To revert back to SMS and apply blocking policies, you must disable RCS.

Resolution

To resolve the issue, you must ensure the following policies are applied:

1. On your EMM console, go to your Knox Service Plugin configuration.

2. Configure the following Device-wide policies:

   Policy	Value
   Enable device policy controls	True
   Call and Messaging Control > Enable call and messaging controls	True
   Call and Messaging Control > Manage RCS messaging	False

3. Under the SMS Controls policies group, set your Blocklist Incoming SMS restriction and Blocklist Outgoing SMS restriction policies as required.

   You can enter a comma-separated list of phone numbers to block. However, we recommend using regular expressions when setting your blocking policies:

   Description	Value	Examples
   Blocks all SMSs.	.*	243553962345678 800-123-4567 9001234567
   Blocks SMSs from +91XXXXXXXXXX and 91XXXXXXXXXX, where X is the specified number.	^\+?91XXXXXXXXXX	911231234567 +911231234567
   Blocks all SMSs for any number starting with 011 (international code).	011.*	011551912345678 0116724980204
   Blocks all SMSs for 900XXXXXXX, where the Xs can be any 7 digits.	(900[0-9]{7}$).*	9001234567 9005557890
   Blocks all SMSs for 900XXXXXXX, plus optional dashes. The Xs can be any 7 digits. The backslash before the hyphen indicates treating the hyphen as a literal character, not as a regex symbol.	(900[\-]?[0-9]{3}[\-]?[0-9]{4}$).*	9001234567 900-9001234 900123-4567
   Blocks all SMSs except for 800XXXXXXX, where the Xs can be any 7 digits.	(?!800[0-9]{7}$).*	800123456 1-800-1234-567 5551234567
   Blocks all SMSs except for [optional digit "1"]800XXXXXXX, where the Xs can be any 7 digits. The international code may or may not be sent by cellular carrier. Some of the possibilities include 1[number], 1-[number], +1[number], +1-[number].	(?![1]?800[0-9]{7}$).*	1-800-1234-567 5551234567 011551912345678
   Blocks all SMSs except for [optional digit "1"]800XXXXXXX, plus optional dashes. The Xs can be any 7 digits.	(?![1]?[\-]?800[\-]?[0-9]{3}[\-]?[0-9]{4}$).*	800123456 5551234567 011551912345678

4. Save the profile and apply the changes to your devices.