We have an issue with number display when using SIP trunk. Currently, we have successfully integrated SAP-BCM call center with CUCM 8.0 using SIP Trunk. During normal call routing, the calls to the agents are passed from Cisco call manager to SAP-BCM. However there is a requirement where the customers call the reception and the receptionist transfers the call to SAP-BCM via SIP trunk. Once the transfer is completed, the agents are seeing the receptionist number instead of the caller's number. Call flow is given below.
Normal Call: DID --> GW --> CUCM --> SIP --> SAP-BCM
If you haven't stumbled across the answer already, you may try a config adjustment on the SIP Trunk. In the Outbound Calls section, try changing Calling Party Selection from "Originator" to "First Redirect Number (External)".