I have plenty of Obi BT experience as well as experience with a Cordless paired to a phone via Bluetooth. Both work equally well in my experience but the Obi gives more options. As mentioned above the Obi is just a BT headset so far as the Cell phone cares. The Obi views the Cellphone as if it is a completely separate service provider with its own SP slot. All of the options you have well using any other VOIP service provider are available for the paired BT phone.
Incoming calls can be routed to phone port1, phone port2, both phone ports, the Obitalk network, the auto attendant, and a lot of other places I won't bother with to keep things brief. The limit is essentially based on your own imagination and creativity. I have even successfully tested sending a Cell call to Skype.
Outgoing calls can be made based on your preference. You could set it up to use your cellphone whenever it is available. You can use a dialing prefix to dial using the cell phone. You could set just one phone port to use it. You could set only certain numbers to be dialed through it.
If you plan to use your cell phone for all outgoing calls whenever it is available the trick is to create a trunk group. Then you use BT1 as the first entry in that group. Set SP1,SP2,SP3,or SP4 as the second entry depending on which service you would like to use when the cell phone is not available. Finally set the trunk group as the primary outgoing service.
One thing you should know is that only 1 cell phone can be connected to a BT adapter at a time. If you plan to have 2 cell phones connected at the same time you need a second BT adapter and a usb hub to accomplish that. Maximum limit 2 BT adapters per obi unit.
