I apologize in advance if this question has been answered elsewhere on this forum. I have been searching the web for several weeks and have yet to find a solution.
I have three regular POTS lines connected to a Grandstream GXW 4104 FXO gateway, each FXO port is setup with its own SIP trunk into Asterisk. I have an IVR built with a custom extension that when a caller presses 1 it goes to the custom extension that plays a recording saying your call will be transferred, it issues a hook flash to the FXO gateway, dials a telephone number of a third party and hangs up to have the telephone company transfer the call. The problem is I haven’t found a way to send a command to the gateway to hook flash. I read on the web I need to send a DTMF 16, or an “r” character. I tried using SendDTMF with the commands mentioned but Asterisk rejects it. I have the latest firmware loaded into the Gateway which does support hook flash, but the problem I am having is sending the message to the gateway to make it do a hook flash. I am using Asterisk 11.
Any help or direction on how to proceed would be greatly appreciated.