The three pricing models, and how to compare them
UK call answering is sold three ways: per call, per minute, or as a monthly bundle of calls or minutes. Per-call pricing is simple but climbs with your call volume. Per-minute pricing rewards short calls and punishes chatty ones. Bundles smooth the bill but you pay for allowance you may not use, and overage rates apply beyond it.
The only fair way to compare them is the effective per-call rate: divide the monthly bill you expect by the calls you expect answered. A £75 bundle covering 30 calls is £2.50 a call. A quote that looks cheaper per month can be dearer per call, which is the number your missed-call maths actually runs on.
Costs that do not show on the price list
Ask about hours first: 24/7 cover is included with some providers, extra with others, and simply unavailable on some published plans. Then ask how time is counted. Billing by the second exists, Face For Business advertises exactly that, but rounding up to the minute is common and quietly inflates per-minute deals.
Also ask what counts as an answered call: some services charge for sales and nuisance calls, others exclude them. And check what a message actually contains. If every answered call still ends in a note for you to ring back, the service has moved your work, not removed it.
What AI answering changes about the maths
Human answering is priced per call because a person can only take one call at a time, and overnight cover means overnight staff. Software has neither constraint, so an AI receptionist like Kalvo sells a flat plan instead: £49 a month for 100 call minutes, 24/7 included, every simultaneous caller answered.
The capability trade is real and worth weighing honestly: a person can exercise judgment a script never captures, while an AI receptionist answers from your knowledge base, books the appointment on the call, and never queues a caller. Our AI receptionist vs answering service comparison takes that question on directly.