Two different things the platform counts separately, and the distinction is most of how outbound is priced.
An attempt is one dial handed to your carrier — connected or not, answered by a person, by a machine, or by nobody. Every outbound plan pays a published per-attempt fee for it. An attempt the platform refused before a dial ever existed is charged nothing at all, which is worth saying plainly: a compliance refusal costs you nothing except the contact you should not have called.
A conversation is what happens once a person answers. It claims a concurrent session, and its minutes bill as AI usage per minute — the per-minute rate prices the AI, not the telephony, which is why it applies on a bring-your-own-carrier account exactly as it does anywhere else, while your carrier bills you separately for the carriage. Reaching the same person on a third attempt is still one conversation, which is why an estimate’s attempt count follows the retry curve while its conversation count can never exceed the size of your list.
The estimator runs on your own numbers: the answer rate you already know for your list, your retry ceiling, your average call length. It leaves the volume discount out on purpose, so the figure you compute can come in above the invoice and never below it. The per-attempt fee, the per-minute rates and the volume-discount floor are all on the pricing page rather than typed into this definition.