CDR change src

Hi Guys,

i hope you can help me.
We´ve got a SIP Trunk from our Freepbx 12.0.59 to a customer PBX.
Our customer sends us a call, the From Header in the invite looks like this:
From: CallerID sip:trunkname@CustomerIP ;tag=cN3mt20jQQD5S

Our customer can´t change this header in his PBX.
Our problem is, in the CDR entry the “trunkname” is set as src.

 calldate: 2017-02-16 10:06:01
     clid: "Seb:CallerID" <trunkname>
      src: trunkname
      dst: XXX
 dcontext: from-pstn
  channel: SIP/trunkname-00000087

dstchannel: Local/FMGL-XXX@from-internal-0000026b;1
lastapp: Dial
lastdata: Local/FMPR-XXX@from-internal&Local/FMGL-XXX@from-internal,62,TtrIM(auto-blkvm)
duration: 2
billsec: 0
disposition: NO ANSWER
amaflags: 3
uniqueid: 1487235961.1376

We see the CallerID in the CallerID(name) field.
Is there any way to change the src in den CDR to the real CallerID instead of the trunkname?