Users Getting Frozen Due to OAuth Token Security Enhancement – Salesforce Voice (formerly Service Cloud Voice) REST API

Salesforce has introduced an OAuth token risk detection mechanism as part of an ongoing security improvement. In certain configurations, specifically orgs using Salesforce Voice (formerly Service Cloud Voice) REST API integrated via AWS Lambda "InvokeSalesforceRestApiFunction", this change may flag and revoke active OAuth tokens, causing the associated Salesforce User(s) to become frozen without any manual action.

• Users in your org are unexpectedly frozen
• Your Lambda function logs in AWS CloudWatch show the following API response from Salesforce:

{
  "error": "invalid_grant",
  "error_description": "authentication failure"
}