In a Microsoft Skype for Business Server hybrid deployment with on-premises Public Switched Telephone Network (PSTN) connectivity, when a Microsoft Skype for Business Online user makes an outgoing PSTN call, the on-premises trunk translation rules take precedence over the user's line URI in the following scenario in Skype for Business Server 2015:
- Calling number translation rules are defined in the on-premises trunk configuration.
- The CallerIDSubstitue of the Skype for Business Online user's CallerIdPolicy is set to the user's line URI.
For all other scenarios, no overrides occur, and the caller ID would be defined by CallerIDSubstitue.