How to make a callback service that, on a certain event, calls one mobile phone, then another and combines them into one conversation?

Question

SIP

In general, there is a task to make a callback service that, on a certain event, calls one mobile, then another mobile, and combines them into one conversation. The duration of the conversation is logged. An almost similar system is used in the Buddhist app .
I don’t understand this at all, tell me how this can be implemented, or at least in which direction to google and which specialists to contact.
Country - Ukraine, if it matters.

Answer 1

API to help you. I don’t know how for Ukraine, but for Russia we use Virtual Office Tools . We solved a similar problem, so we set it up in a day and rejoice :)

Answer 2

Any server in one way or another. Example:
Asterisk:
pbx*CLI> core show application Bridge
pbx*CLI>
-= Info about application 'Bridge' =-
[Synopsis]
Bridge two channels
[Description]
Usage: Bridge(channel[,options])
Allows the ability to bridge two channels via the dialplan.
The current channel is bridged to the specified 'channel'.
Options:
p - Play a courtesy tone to 'channel'.
This application sets the following channel variable upon completion:
BRIDGERESULT The result of the bridge attempt as a text string, one of
SUCCESS | FAILURE | LOOP | NONEXISTENT | INCOMPATIBLE

Answer 3

just pass the numbers to the callback script and everything
exten => s,n(vhod),Set(CALL=89031234567)
exten => s,n,Set(DESTINATION=from-internal-custom.89037654321.1)
exten => s,n, Set(SLEEP=2)
exten => s,n,System(/var/lib/asterisk/bin/callback ${CALL} ${DESTINATION} ${SLEEP} &)