Mobotix might work. They just introduced their MXDisplay+ Outdoor model which has Bluetooth support. The MXDisplay is a small touchscreen that mounts inside the house (but is weatherproof, hence the name), with a T25 camera station that would be at the doorbell location.

So, a visitor rings the doorbell (T25 button), and you receive a notification at the Display inside, or at your phone/ipad with the app. You can see and speak to the visitor, and open the gate/door.

It works as a standalone setup or can be integrated. Not the cheapest solution, but it's also got a million other feature which you may not actually want (RFID cards, message recording capabilities, etc...) The camera is a 180* recording camera that can save to an on-board SD card. All the devices are PoE powered as well, so the wiring is straight-forward.

I have an installation that went quite well, and has been reliable although I have NOT used any of the Bluetooth features. My only hiccup was a camera that acted funky right out of the box that I'm trying to return, and they're being reluctant with the RMA. Other than that, the support has been great.

EDIT: One more thing - I used the Mobotix because the homeowner required that there be a numeric keypad outside for visitors to key in a code to open the gate. That was something I couldn't get elsewhere (at the time).