Voice over network?

Question

Data transfer

It is necessary to establish a connection between clients: on the one hand there will be mobile devices, on the other, web or also mobile phones. Both parties connect and a conversation begins.
Since there was no such experience yet, accordingly, I don’t know yet in which direction to look and how best to implement it. Therefore, I ask for advice, point out what to look for first of all, any or frameworks, in order to avoid some typical problems: loss of sound, poor transmission quality.
Do they do it P2P, or does the whole stream run through a server. In the event of a poor connection (from Wifi to 3g), how is the issue resolved - to degrade the quality of the transmitted sound?

Answer 1

IP telephony