Attended transfer with managerApi

Sorry for my english!!!

I want to send a DTMF sequence on a channel (SIP phone)

Why ? because I want to manage the attended tranfer whith the manager API and I don’t know any other solution!!

The API PlayDtmfAction appear as one solution but there is a problem with my asterisk version (unknow command from manager)

Have you got a idea and information on a patch ?

Thanks for help !!!