I have A Couple Grand-stream BT 100 Phones that have me Beaten and Shaken! I have them configured remotely and they register successfully with 3CX and i can make out going calls quite well but when i try to buzz there extensions they will ring but when i pick up the headset the don't connect and the incoming line i am calling them on still rings when i hang up the phone 5 seconds later the phone starts to ring again(without even calling it) you can pick up the phone to dead air, hang up and 5 seconds later it starts to ring again. to (you guessed it) "Dead Air" i have softphones that work perfectly remotely and an ATA device on a Fax also works perfectly remotely but these stinking grand streams have me whooped! anyone have any experience with these? are there magical settings i am missing on these phones? also there work fine locally so i would almost think it was a nat traversal issue if it was not for everything else working..