Okay walk me through the process.No authorization is required
No sim card is needed
No software api or sdks are needed
You can verify it yourself using any sip client such as Zoiper or X-lite, and the data that is returned to you when you register with any voip / sip telephony service provider
In many cases, it is possible to register completely free of charge, already having the possibility to receive calls from any telephone on the public telephone network.
Credit can be purchased, even for a minimum amount of 6-12 euros, only when it is necessary to make an external call
The VoIP client calls the other VoIP client by connecting to a server and the server will redirect the data packets (sounds, events, etc...)
Below is how a normal VoIP SIP works :
and below is the process of your request :
and how does the b4a client connects to a public network? what is the middle ware server? how is it forwarded?? what is the receiving point that will transfer the packets??