1. mak sure the calling flow, the caller is customer's mobile, call the DDI number in U1910, the callee is the IP phone in U1910, phone number is DDI number.
2. Check Configuration in U1910, whether follow the product document.
3. Use UCMaint to collect the log and check whether the calling party number was sent to U1910 via PRA.
The switch mode in UCMaint should be set as: