Research pay before the first conversation, not after the offer

Look at posted ranges for the same title, same seniority, same city, from several companies. Then decide two numbers: what you would accept, and what you would decline. Having both settled in advance is what stops you from agreeing to something on a call and regretting it that evening.

If a market genuinely has no public data, ask a recruiter directly what the band is for the role. It is a normal question and refusing to answer it is itself informative.