How do Caller ID replacement services work?

Question

SIP

How do services for changing the phone number when calling (Caller ID), such as xho.ru, sip-system, black-voip and others, work?

Answer 1

What's so amazing.
They deployed a telephony server, rented a bunch of numbers in different countries. You connect to them via SIP, they route your call and release it through their numbers, respectively, party B sees the operator's number, and not yours.
A telephony server works in a similar way in any company. When you call from an internal phone to the city, the client sees the number of the city line, and not the short internal number)