I like Skype. I liked it better before Microsoft took it over, but I guess I’m glad that the developers got their cash.
Anyway… like all these things, it has sucked me in. My ink-on-paper copy of phone numbers I use is out of date. In any case, I might lose my smartphone, or it may die. And I don’t want my contacts “in the cloud”, thank you very much.
You can back up your Skype contacts to a file-
Go to secure.skype.com with a browser. You can enter that URL, or get there from your Skype app.
Once logged in, you should be at… or be able to get to… secure.skype.com/portal/overview
Near the bottom of that, but on that page, under “Account Details” heading, under “Settings and preferences” sub-heading, there are links for downloading various things.
For your contacts (people you call and their numbers, plus other stuff), you use “Export contacts”. (You guessed that?)
That will give you a .csv file, which you can load to spreadsheet (LibreOffice “import csv” help) or text editor or wordprocessor. I’d recommend a spreadsheet. (For LibreOffice Calc, the delimiter is a comma, as is usual.)