Cost per AI reply is measured from live Delta AI Response System traffic between 26 May and 21 August 2026: 2,242 real AI turns across 544 real conversations, with seeded and demo traffic excluded. The median reply cost $0.02 is the low end of the range and the mean $0.03 is the high end.
Conversation length options are the measured median (2 replies) and mean (4.12 replies) from the same sample, plus a longer case. SMS delivery assumes 2.66 sends per reply, which is the measured average over 1,220 real outbound texts, at the platform rate of $0.0079 a segment. Voice is $0.32 a minute, measured over 797 real calls of 30 seconds or longer.
These figures run high rather than low. A large part of the sample is cold-start traffic where the prompt cache is written fresh on nearly every conversation, which a busy account amortizes away. We would rather quote you a cost you beat than one you blow through.
Model prices move. Treat this as an estimate to size the decision, not a quote.