I am working on deploying an SL2100 and have found the limitation regarding department groups in that you cannot have any forwarding enabled for extensions that are a member of the department group. I was thinking I would just use a virtual extension key to get around the problem, but then I found that a virtual extension key cannot be assigned to a 3rd party SIP phone. Ideally I would like to find a method that would allow a pilot number to ring a group of Grandstream WP820's that are connected to the system, while retaining their ability to have individual mailboxes assigned to them. The WP820's are working well with our old DSX, but it's time to upgrade. I'm hoping there is a way to make it work, thank you!