Mutual NDAs are optional for the first discovery call. Most discovery calls happen at a level where NDA coverage is not yet required: the conversation is about operator size, target markets, current position, and the situation the operator wants to discuss. None of that requires NDA coverage.
If your internal policy requires an NDA before any external conversation, send your standard mutual NDA in advance and I will sign before the call. Once an engagement letter is signed, the work is under mutual NDA from that point forward. Operator names appear in case studies only with explicit written consent and are anonymised by default.
The honest read on NDAs at discovery stage: if the question you want to ask cannot be discussed without NDA coverage, the better shape is probably a paid diagnostic engagement from the start. A 30-minute call cannot do justice to information that is genuinely sensitive enough to need NDA coverage; a structured two-week diagnostic with NDA from day one can.