CDR - all extensions in a queue busy

[Simone Rota]

Hi,
A customer call a Queue completely busy, he waits 30 seconds and then closes the call.
In CDR I'm going to find a call Started and Ended 1 second later. Duration 0 seconds.

How to snow in CDR that he waits 30 seconds or more? I need it to check our SLA.

I know I have a Report of Abandoned Queue Call but I cannot join every time CDR and the Report

Thanks
Simo