You imply you want Arduino to tell the phone that Bluetooth is connected. It cannot do that and it is a pointless exercise anyway. The phone will tell you that it is connected to Bluetooth. Bluetooth has two communications facilities
by wire with Arduino
by wireless with the phone
Neither the phone nor Arduino know this, and it is down to you to make both work properly.
You might find the following background notes useful.
I understand he state pin doesn't work with all versions. If you have succeeded in that, I guess you can then send a confirmation to the phone. You could always echo whatever you sent from the phone. That should always work. The above programme does that - phone initiated, not Arduino initiated. You may only need to do either of this in Setup.