Meet some questions to implement a call back function with d

Meet some questions to implement a call back function with dial plan…
I am trying to implement a call back function with dial plan. Basically, it works in this way: a phone, for example with the number of 1234,
1234 phone dials in the Asterisk PBX,
As long as the Asterisk PBX knows that the phone 1234 dials in, the asterisk PBX will hand up the call immediately.
After that Asterisk PBX will call 1234 phone with a dialing tone.
1234 phone will answer this call from PBX, and 1234 will hear the dialing tone.
1234 phone will dial a number for example 5678#
Next Asterisk will bridge the call between the 1234 and 5678.
I was thinking that possible this function could be implemented by dial plan. But I do not know for sure how this function could be implemented.
I am wondering if someone has idea about this.
Thank you

voip-info.org/wiki/view/Asterisk+cmd+DISA