i think readers do it for a few reasons:
- like Sapphire does, for instance, to start the call and verify they can actually make a connection without much commitment from the caller (which encourages those riding the fence on whether or not to call to just do it. nothing lost)
- as a somewhat of a thank-you for your patronage. like, next call a few minutes are on me
- to encourage you to actually call. once you do, 9 times out of 10 you stay on the call longer than the free mins. it's like a coupon. so, you will choose THIS reader because it's somewhat of a discount to call them