How to make a function for an application to be able to speak in Android?

Question

Java

How to make a function for the application to be able to speak? In fact, what would you say like on Viber. How can it be implemented? I didn't find any information on the net. Security can be omitted.

Answer 1

If you want to make a "dialer" - that is, communicate using your application by voice, then you need to use a VOIP engine. What can I advise from my own experience:
1) CSipSimple - Open Source application based on pjsip. 1M+ installs on Google Play, well-structured code, can be used as a library (the author suggests doing this)
2) PortSIP SDK - paid, but, subjectively, the quality is better. It is expensive (thousands of dollars). There is a trial with restrictions. You will have to write the bindings around the SDK yourself if nothing has changed. But support answers questions and really solves problems.
3) linphone, as mentioned above. Personally did not work, but the thing is quite well-known in its field. Worth a try.
In addition to the software part, you will need a server - Asterisk, for example. You can use third-party services - I will not advise anything here.