How to create a telephone gateway?

Question

Telephony

We need some kind of telephone gateway, which will be a "laying" for forwarding to the main number. It is necessary that the site has a replacement number, the call to which is redirected to the "real" number of the user. Condition: the number of users to be redirected in the future is up to 10000 per number or pool of numbers.
Questions:
What are the online telephony services that will allow you to implement this?
What technology sec to use for self-configuring the server?
What to do with the regions of Russia, in order to exclude long-distance communication?

Answer 1

1. Perhaps it will allow to implement Zadarma - it is better to consult with managers. From your question it is not clear by what logic the subscriber / pool of numbers will be selected
   
2. For self-configuring the server - Asterisk (or FreePBX). On the plus side, great flexibility. Of the minuses - you need a qualified specialist
   
3. Here I see only 2 options - rent regional numbers, or rent a number 8800 *