Filter Call Log by User/Agent?

Revise your question. Are you using API? Are you build an app etc.?

You can check call logs per extension using extension call log api

/account/~/extension/[extID of the agent/user]/call-log . There is no filter for account level call log currently for filtering out for per extension ... u can build a logic around ur code to check the account level call log response and check out extension involved in the call leg.