Hi, feixue!
Have a good day!
Please see the following steps:
Log in to the uPortal as user admin. Choose Management > Resource > Number Management and click Create.
Configure a DID number. The system automatically sets Calling number display to Calling party long number (DID).

Click the System Configuration. Choose Routing > Number Change and add a number change data record AAAA in which Number Change Type is set to Change to unified number.

Choose Routing > Prefixes and click New. Set Service Attribute to Intra-office call, and Intra-office Long Number to Yes.

Choose Routing > Prefixes and click New. Set Service Attribute to Local call and Calling Number Change Name to in number change data record AAAA.

Click OK.
I wish your question is resolved!
Best regards!