[SR-Users] pdd value

Hi all Question about an additional cdr information. We need to get the pdd value - means a time value till the user gets a ringback or an error- to track the delay, till a connection is done --> quality issue for customer. 5.6.1 Definition of Post Dial Delay Post Dial Delay (PDD) is experienced by the originating customer as the time from the sending of the final dialled digit to the point at which they hear ring tone or other in-band information. Where the originating network is required to play an announcement before completing the call then this definition of PDD excludes the duration of such announcements. How can this be done in Kamailio? We use the carrierroute module with different fallback carriers. Kamailio version 3.3.5 Thanks in advance Oli