Do-it-yourself callback service?

Question

Telephony

Recently, a lot of callback services like callbackhunter.com have
appeared. There was an idea to implement something similar on the server side in order not to pay third-party services, but I'm not particularly familiar with ip-telephony.
Are there any guides on how to implement this and what equipment will be needed?

Answer 1

On the asterisk, this is done quite simply. How much would you offer to write such a guide?