Nivex 🐧 📻@ND3JR Callcentric has their Dollar Unlimited (incoming) plan. You can only pick from certain area codes though. In the age of cellphones that won't much matter. You'll then need an outgoing plan. If you pick the cheapest one (120 min) your total bill will be under $5.
voip.ms pricing is similar, though metered slightly differently. You can likely end up with a cheaper bill, but they don't include as many freebies (eg: you pay extra for a number to call other customers via SIP).
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