When someone dials the employee extension (x101) directly, the system can ring your routing 1 option (for e.g. skype) first and then try your routing 2 option (for e.g. mobile number) if the first fails. Your skype voicemail must be turned off for this to work. As skype voicemail will preempt and take over the call instead of zaplee.
When someone dials a department extension (e.g. Finance x1) the system can only call the routing 1 option of each employee (for e.g. skype in this case). The system is designed this way because most companies have multiple people in each department.
If still you would like to use department routing and want the call to go to skype and next to your mobile when skype is offline.
Then the workaround for this is to create 2 employees...1 with your skype id as the first routing option and another employee with mobile number as the first routing option. Add both of these employees to the department and this would take care of this issue.
Another workaround is - If you don't want to add another employee to your account, you could give your direct extension in the company greeting -- "to speak to a real estate agent, dial extension x101".