A Sydney man called triple zero and said "I killed my wife" before later pleading not guilty to murder.

The NSW Supreme Court on Wednesday heard the call Shahab Ahmed made to triple zero about 10 minutes after stabbing Khondkar Fariha Elahi to death in their Parramatta unit in February 2017.

Shahab Ahmed and wife Khondkar Fariha Elahi.

In it, the operator answers, confirms his address and then asks "what happened?"

"I killed my wife," he said.