Yes, if the PRI carrier allows it. Many times they restrict the outgoing caller id to numbers that are associated with the account.
For R9.0 go to System > Twinning and check the box for "Send original calling party information for Mobile Twinning"
Run Monitor, check all the boxes on the ISDN tab, run System Status, go to the PRI and click on Trace All.
Place a call that is twinned, and through Monitor and SSA confirm that the incoming caller is is the "calling party" on the outbound call. If that original caller id is not received at the destination, contact your carrier to allow the pbx to control the outbound caller id, and open for ANY number.
Finally, make sure you are sending a valid number on emergency calls