I have a question regarding the information posted during an ACE callback. There is a discrepancy with the session call identifiers.

Here is the response after initiating a successful session call:
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<soapenv:Header/>
<soapenv:Body>
<loc:makeCallSessionResponse xmlns:loc="http://www.csapi.org/schema/parlayx/third_party_call/v3_4/local">
<loc:result>8dcfe664-1851-4a4a-80ef-4ffee79aa99c</loc:result>
</loc:makeCallSessionResponse>
</soapenv:Body>
</soapenv:Envelope>

Here is a notifyCallEvent post:
<?xml version='1.0' encoding='UTF-8'?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Body>
<notifyCallEvent xmlns="http://www.csapi.org/schema/parlayx/call_notification/v3_8/local">
<correlator>AvayaCallBack-Test-x18</correlator>
<eventNotified>
<callEvent xmlns="">CalledNumber</callEvent>
</eventNotified>
<callingParticipant>tel:T11017#1;phone-context=dialstring</callingParticipant>
<calledParticipant>tel:+1234567</calledParticipant>
<callSessionIdentifier>83502477-e344-48e0-9b60-6558fb07f6b2</callSessionIdentifier>
</notifyCallEvent>
</soapenv:Body>
</soapenv:Envelope>

The element callSessionIdentifier is defined as the "Unique identifier that identifies the call session." My question is: since the id returned after a successful session initiation does not match the one from the call event, how do we get the identifier that will be used in the call event BEFORE we receive the event?

Thanks