Decide what the first visit is intended to achieve: stop active flow, leave unsafe equipment inactive, open a blocked path enough to prevent return, or identify a likely source. Ask what diagnosis and the service-call price include. Access, parts, camera work, permit activity, cleanup, drying, sanitation, disposal, and finish restoration may be separate.
Set the price or work threshold that requires another conversation. If opening a wall, removing a fixture, excavating, or replacing equipment is suggested, ask which observation justifies it, where the work stops, how the area will be protected, and what finding would change the plan. Record every closed valve and fixture that must remain unused.
The provider conversation should begin with identity. Request the legal contracting name, exact license for regulated work, insurance evidence, Cohasset coverage, arrival arrangement if offered, and recording disclosure. A call connection is not proof of any of those points, and this site did not observe a routing test.