Submitted via MS WhiteSpace Program on behalf of Mudit Agarwal, ASSC CONSULTANT GD WSP 4613 - Missing Unique Auto Number Functionality In CRM 2013 Online mode where we can deploy plugins only in sandbox mode, there is no guaranteed way through which we can generate unique numbers in the custom fields of custom entity. Like case, opportunity entities give this functionality OOB. Customer: DSM Customer Scenario: We are working on Upgrade Assessment of a Client DSM, they have multiple tenants in CRM 4.0 and want to move to CRM 2013 online environment. One of the key requirement is to have unique number generated like Case or Opportunity. But unfortunately we don't have any supported way of doing this. Even locks are not guaranteed to give a unique number sequence all the times. They were using Mutex class of Threading to make sure unique ness. But such classes don't work in sand box environment.