I have been trying to set up Ekiga to videophone my partner. I have registered both laptops with ekiga.net, but the sip address of my partner is rejected by ekiga softphone with the message "globally unacceptable". I have tried two different sip accounts for her with the same result. At my end everything went without a hitch. None of the major alternatives to skype(which continually loses sound) seem to load without problems or require me to install on a mobile. Any Ideas welcome including a straight forward skype alternative.
Thanks in anticipation

There are Skype packages for Linux, though rumors continually surface that its days are numbered. You may have to get it from the Skype website. I have used it, albeit infrequently, and it works okay.

A web search for "ekiga globally unacceptable" turned up a number of posts and forum threads on this topic, included several possible solutions.

Afterthought:

I've also heard good things about Discord, but I haven't used it: https://discordapp.com/company