So, instead of requiring your customers to recite their passwords to unidentifiable strangers over the telephone, you could use a randomly generated PIN instead. Then, you could present that PIN inside the customer's account, where they could read it out to you.
This carries all the advantages of making sure the person you're speaking with has their password, but with none of the downsides, such as giving the password to a customer service member in plain text (thereby allowing them to write it down,) or giving your customer service staff a mechanism to test whether customer passwords