How to merge two external calls via sip?

Question

linux

Hello! There is a task to make two calls via SIP to mobile phones and as soon as people pick up the handsets, combine them into one call. As I understand it, this can be implemented through an asterisk or freeswitch, but I really don’t want to study them and fool around with them at all. I came across the linphone library - did anyone work with it - is it possible to implement this there? Or maybe someone else has some solutions?

Answer 1

In order for people to talk to each other, you need a SIP server through which data will be exchanged. Phones do not communicate with each other directly. SIP is not a p2p protocol. Asterisk and FreeSWITCH can act as such servers. The library you mentioned (judging by the description on Wikipedia) is just a SIP client. For the client besides the server is necessary.
If you do not have the desire or the ability to deal with the PBXs mentioned above, then most likely a solution based on the API of some ready-made cloud platform will suit you. Here is an example of how this can be implemented: https://habrahabr.ru/post/226057/

Answer 2

In asterisk, this is done through call files - after picking up the handset, you send the call to the conference.
PS search in Google - "automatic collection of the conference" will be examples in bash, php and everything else.
If the hands stick out of the right place - work for a couple of hours along with debugging.
Don't reinvent the wheel - everything is up to you.