Attaches a resource-based policy to a End User Messaging SMS resource(phone number, sender Id, phone poll, or opt-out list) that is used for sharing the resource. A shared resource can be a Pool, Opt-out list, Sender Id, or Phone number. For more information about resource-based policies, see <a href="https://docs.aws.amazon.com/sms-voice/latest/userguide/shared-resources.html">Working with shared resources</a> in the <i>End User Messaging SMS User Guide</i>.