Know which comparison you are making, because it decides the answer. Against a general-purpose voice platform these look limited. Against a live answering service at $300 a month they look like a bargain. Most people buying here are running the second comparison without realising it.
The question that settles it: what happens today when nobody picks up? If the answer is voicemail nobody returns, almost anything is an improvement, and you should optimise for how fast you can get it live rather than for capability you will never configure.
Slang.ai and Sameday are the vertical options, scoped to restaurants and home services, with the booking logic already built. You pay more per month and skip an integration project. That trade only makes sense if the integration is genuinely the hard part, which for a restaurant taking reservations it usually is.