You can use the system transfer feature in Unity 4.1 and later (it may have been in 4.0(5) but I don't have a version here to check). There are two types of system transfer you can access - subscribers (requires authentication but uses the restriction table associated with that user's COS) or caller system transfer which uses a single system wide restriction table. Both allow you to dial any number and have it do a release transfer to that number provided it is allowed by the appropriate restriction table.
Both conversatons can be accessed by mapping a user input key or by creating a routing rule that goes to one of them. In Unity 5.0 the subscriber system transfer conversation will also be allowed directly from within the subscriber conversation itself.
I was just following some posts here and would just say to keep in mind you will be using a lic seat for each subscriber you add, why dont you use call handlers instead and change the transfer settings to the extensions you want.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...