In extensions:
exten=> 2020,1,Answer
exten=> 2020,2,Set(DYNAMIC_FEATURES=mixmonitorpeer)
exten=> 2020,3,Ringing
exten=> 2020,4,Wait(2)
exten=> 2020,5,Queue(support)
exten=> 2020,8,Hangup

In features:
[applicationmap]
mixmonitorpeer => *0,self/callee,MixMonitor,Callerid(num)|ba

I need to pass the CallerID number