How do you keep your phone number when you are abroad for a long time?

Question

Telephony

I'm going to leave to live in Thailand and possibly Vietnam and neighboring countries. I want to continue to work in the same mode as now.
So the question is: how do you save your mobile number so that you can write SMS and call?
What solutions do you use?
I previously looked at Skype, that it has an option that I can call Moscow from Skype and receive calls, but what about SMS or iMessage, for example, and where in this case my SIM card will remain with me (but roaming will eat everything) or stay in Russia?

Answer 1

https://roamerapp.com/en/

Answer 2

avoapp.com