If they send sellers after that we usually just ask them to leave and send the engineers. I've seen quite a few pouts but it's impossible to get accurate product information out a seller, they just tell you what you want to hear.
I've never been in contact with IBM before but I'm not surprised about your experience.
https://youtu.be/XOR8mk0tLpc?t=54 [0]
[0] Sales call scene with Joe and Gordon in Halt and Catch Fire: Season 1 Episode 1
[1] https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(TV_series...
When I took sales calls, I would usually sit through the intro pitch from the salesperson, and if it seemed in the ballpark, I would cut the call short and ask to be put in touch with product/engineering by email. And if I liked what I saw, I'd go back to the salesperson for pricing, etc.
The biggest issue I've had in the past is that I ask for a feature and the salesman say "no problem" and when it's time to implement what I asked for is a custom feature that they can build for €100k.