At least in the US, VOIP providers (think google voice or twilio) interconnect with telephone companies similar to how landline/cellphone companies interconnect with each other, so #1 and #4 are essentially the same. The only difference is what the "from" number appears as. If you look at the price lists of voip providers, you'll note that the only factor that determines the price is where you're calling to, not where you're calling from.
That provider is either only providing service to one country (very likely because this is separately regulated in every country), is showing you prices specific to your country, or is doing #1 and making themselves liable for spam.
>That provider is either only providing service to one country (very likely because this is separately regulated in every country),
twilio can hardly be described as "providing service to one country", and has the same price list whether I'm using an American VPN or Dutch VPN:
https://www.twilio.com/en-us/voice/pricing/fr
You see how it says "local"? That means a local call.
That doesn't make any sense when you look at the other options, one of which is "Mobile calls", but no "long distance" or "foreign" option. Moreover twilio operates over the internet. There's no concept of "local" on the internet. The concept of long distance only really exists for landlines and cell phones, but even in the latter case it gets blurred because of wifi calling. You could have a SIM for a US carrier but be using wifi calling from hong kong, and that would still be a "local" call.
Exactly, no long distance or foreign option. So these must be local calls, meaning they are made from a French twilio number to a French number.
>So these must be local calls
No, you're just reading too much into "local". The price page for US also only has "local" only, but I know for a fact that "long distance" calls work fine.
https://www.twilio.com/en-us/voice/pricing/us