What are the programs for voice and video communication that currently work in Windows XP (and preferably other OS) ??

Question

Windows

What are the programs for voice and video communication that currently work in Windows XP and preferably also a client under Linux ??

it is necessary to make a conference, at least 1-1 (remote client Windows XP, I have Linux)

PS: most of the missionrs are not installed.
Viber installed (from offsite, for Windows XP, there), but it does not work, reports that there is no Internet = -O

PPS: no need to write update the OS, etc. etc.

Answer 1

Old versions of MyChat worked. But in the new ones, support for calls in XP has been cut out, and the messenger itself works.