CDR report with calling DN in blank

[Luis15]

Hello all!

I need your help for try to understand the beahivour of some calls. I am working with a client that detected many calls with destination of a specific country (Venezuela in this case). But when I check the CDR records, most calls has the "CallingPartyNumber" field empty.
I've been reviewing the meaning of this field being empty, and what I found defines: "For server calls, where Unified Communications Manager originates a half call without a calling party, this field can remain empty." However, I do not understand these types of calls yet.
When I review them at the RTMT level, I see that there is a negotiation between an IP of an E1 and one of the client's Subscribers.

Another field that I see is the “finalcalledPartyUnicodeLoginUserID” field, which appears with the value “\” in all these calls. And I do not understand what this value means.
Someone could  help me with these queries to understand these calls?

Thanks in advance!!!

[VoIP Engineer]

The field “finalcalledPartyUnicodeLoginUserID” will show the CUCM end user that is associated with the device that answered the call.  If this is not populated, and this call was answered by a an end user, then you may not have your devices associated with CUCM end users.

For the missing values in "CallingPartyNumber", if this is an inbound call, it could be that this information is not being received from the PSTN.  Possibly a misconfiguration or teleco issue.

You may want to look at a third party billing server to help you understand these fields.  I recommend VoIP Detective because there is a free version.