[Terr_]

Yeah: Any legitimate institutions will have no problem giving you information (like an extension-code) that you can use to re-contact them back via official channels. (This does depend on not being tricked by going to a fake website with fake contact-info, of course.)

Anyone who threatens you with fines/arrest/whatever for ending the call early is a scammer.

[trod123]

This isn't necessarily true.

For example Equifax's TheWorkNumber won't do this (companies that don't do background references/verification of employment use this service), and their representatives and processes seem to follow similar practices employed by scammers.