How are two subscribers connected, programmatically?

Question

Telephony

Maybe I didn't phrase it that way. The crux of the matter is what. How to make the operator or I don’t know who called number 1 and how he will pick up the pipe called number 2. Ie connected 2 phones, 2 subscribers.
I know there is something called a callback, like a callbackkiller or a callbackhunter. But there is expensive + there is a subscription fee.
I want to figure out how to implement this functionality on my own. Maybe there are some api services?
Or is it done only on your server.. By installing various complex software?
I hope the question is clear) I want to connect 2 phones cheaply, like through Dorinet, for example, call there about 1.5-3p a minute maximum

Answer 1

Good afternoon!
Install Asterisk.
Write the desired context that would call the number you need, and then connect to some other number.
Or use Originate via AMI. You can hang REST and HTTP on it and do it with a button in the web face.
These are just a few of the options. It all depends on your skills and capabilities. You are extremely unlikely to find a ready-made dock "from" and "to" step by step.
Or set the task to knowledgeable people and you will be set up on your server.

Answer 2

It is not clear what is at stake.
About SIP without PBX? About direct IP calls over the Internet without registration?