Feedback agent answer on remote system

Hi,
I have a freepbx 16 with a sip number registered in and a sip trunk to a contact center. When a call come in the freepbx send it to a call center by sip trunk. Immediately a queue answers the call, after some time an agent answers to the call.
What I need is to know the time when an agent of the remote call center answers to the call (to know the waiting time of the caller).
I thought of the following solution:
I send, in the sip header a channel variable with uniqueid, to call center. When an agent answers, it opens an url and send the uniqueid received. At the url side a php script will record in a db uniqueid and answer_timestamp. When I need to know the waiting time I will run a query with a join on uniqueid on the asteriskcrdb.cdr table and the table of my db with uniqueid and answer_timestamp.
The solution seems complex to me, is there anyone who has a simpler solution?

Are you looking to know the wait time of every single call in a queue or just the average for all calls into a queue?

I need to know the time when the agent answer, thanks

Wouldn’t that information be available under Report → CDR Report?

Hi,
under cdr report isn’t possible to know the time when the agent answer. When the PBX send the call to the call center the call is answered by a queue and after an agent answer. I need to know when the agent answers.