One flat tier, instead of a phone-system subscription plus an AI add-on.

Two Bills, Not One

Sona cannot be purchased on its own. It's an add-on exclusive to Quo (formerly OpenPhone), which means the real cost of AI call answering is Quo's base per-user plan (from $15/month annual, $19/month-to-month) plus Sona's own tier (from $25/month for 40 calls). For a solo operator, that's a minimum of roughly $40/month across two products before any meaningful call volume — compared to Phone Desk's single $29/month Solo tier that includes both the number and the AI.

Per-Call Pricing at Scale

Sona's per-call rate scales from $1.00 down to $0.45 depending on tier — a genuinely different unit than Phone Desk's per-minute billing. A short 1-minute call and a 10-minute call cost Sona the same per-call rate, which can favor businesses with typically brief calls and work against you if calls run long. Phone Desk's per-minute bundle does the opposite: short calls use less of your bundle, long calls use more.

What You Get From Quo Itself

To be fair to Sona, the Quo platform underneath it is a real, capable business phone system with shared-inbox texting, call recording, and team collaboration features — not just infrastructure to run an add-on on top of. If you specifically want that broader Quo phone-system feature set and AI answering is secondary, the combined price may be justified. Phone Desk doesn't offer that broader phone-system layer; it's intentionally just the AI answering piece.

Setup Complexity

Because Sona lives inside Quo's call-flow builder, getting AI answering working means first setting up a Quo account and phone number, then configuring Sona within it — two products to learn. Phone Desk's setup is a single guided flow: pick a tier, provision a number, the AI is answering within minutes.

Can I buy Sona without a Quo subscription?

No — Sona is exclusive to Quo (formerly OpenPhone) and requires an active paid plan. It's not available on free trials or as a standalone purchase.

What's the real minimum cost to get AI call answering with Sona?

Roughly $40/month for a single user: Quo's cheapest plan (~$15-19/month) plus Sona's cheapest add-on tier ($25/month for 40 calls). Phone Desk's equivalent is a single $29/month tier with no second subscription.

Does Phone Desk include the broader phone-system features Quo has, like shared-inbox texting?

Phone Desk includes two-way SMS on the same number, threaded into the same inbox as calls, chat, and email on the full platform. It doesn't replicate Quo's full shared-inbox team-texting feature set, which is a more phone-system-focused product.

Is Sona's per-call pricing better or worse than Phone Desk's per-minute bundles?

It depends on your average call length. Sona's flat per-call rate favors short calls; Phone Desk's bundled minutes favor predictable monthly costs regardless of how long individual calls run, with per-minute overage past the bundle.