Hi Emmanuel, was looking into this same thing and I have some additional questions, if you could help. What does it currently do if the transfer isn't succesful? Does it just hang up? Is there any way to send an additional message to the user to let them know that the call transfer failed or something like that? What other tools are you exploring on how to get it done? Please let me know if you have any success there, or if you have any insight as to when VAPI will develop this feature. Thanks in advance!