Hi. I have a strange application where I would like to get a PSTN gateway to send a "flash" to the incoming line. I think its easier if I explain how I want the sequence to work. 1) Incomming call rings PSTN line 2) Grandstream 4108 sends invite to 3cx and phone(s) ring. 3) IP phone answers and the call is connected -- so far this is all good -- 4) "flash" button is pressed on IP phone and event 16 is sent in the RTP to the 4108 5) 4108 applies a flash to the line -- This is the bit i'm stuck on -- As far as i'm aware the 4108 will support sending a flash on the line but the invite message that is send out only supports events 0-11. I think this gets passed on the the SIP phones who don't give the option to send a flash because the event is not supported in the invite. has anyone done this successfully before? does anyone have any idea on the settings I need? note: it does not have to be a Grandstream FXO device. It can be another device if people have had any joy.