Dialogic M7324 사용자 설명서

A transferred call can be aborted at any time (prior to completing the transfer) 
by pressing the appropriate appearance key where the original call resides. 
The application can perform this only in a supervised transfer mode. For 
example, if the original call resided on the first appearance (Feature Key 09), 
dialing dx_dial(<ESC>KA) will bring the original caller back to an active 
state.  

An application answers a call and plays a greeting message prompting the 
caller to enter the extension they wish to reach (the caller enters 221). Using 
the dx_dial( ) function with the dial string (&,221), the application attempts to 
transfer (supervised) the call to extension 221. Call progress analysis is used 
to determine if extension 221 is answered, busy, or there is no answer. If 
extension 221 answers, the application hangs up and the transfer is complete. 
If the extension is busy or not answered, the application reconnects to the 
incoming call and plays a message asking the caller to choose between 
accessing voice mail or transferring to the operator.