You can setup a outdial mailbox and forward your calls to that mailbox. If you have the means to do a hook flash, then you can flash transfer off of the outdial box and free up the co for another call. If not, then you have to use the outdial as a trunk to trunk and you will have a line loss issue with the caller. You can adjust the co to co gain, but it only helps a bit. This has always been a problem with the ESI. The newer CS series addressed this and it is so much better! Keep in mind that once your call forward to the box, every co call to your station will follow forwarding (24-7).