How do I fetch the conversations which do not have a flow at all?

[Aniruddha]

I have a requirement to fetch conversations which do not have any flows(i.e. direct phone calls which does not use a flow)

I am using below segmentFilter in my query, but it fetches all conversations; with and without flowIds.

Query 1:
{ "dimension": "flowId",
"operator": "notExists"}

** notExists- Whether the dimension is absent.**

Query 2:
{"dimension": "flowId", "operator": "exists", "value":null}

Both queries give same results.
I think, the query is checking if any of the segments/session of the conversation does not have a flow and fetches those. This can happen in a normal scenario and hence fetching a lot of conversations!?
But, I want conversations for which none of the segment have flowId.
Is there a way to do that?

[tim.smith]

You'll need to use post-processing to refine the data set based on that criteria. You cannot apply a filter to say that all segments do not have the value; using not exists is only useful when applied to conversation level dimensions (like conversation end not exists) or when combined with other predicates using the and operator (meaning "this and not that" applying to the same segment).