How to use your number from another country without overpaying for roaming?

Question

mobile connection

There is a mobile number in Latvia and there is a number in Russia. I am here and there, roughly in half.
The task is to be able to receive calls to a Latvian number while in Russia, and vice versa, while in Latvia, to receive calls to a Russian number. However, I do not want to pay for roaming. It would also be nice to be able to call from these numbers. I hope there is some way using internet calls.
I can leave my Latvian SIM card for the duration of my stay in the Russian Federation, for example, with a mobile phone in Latvia, and vice versa. You need to somehow set up call forwarding over the Internet.
In which direction should I look in this case? What technologies could I use?

Answer 1

Skype. But in general, don't duplicate questions.
How to use your number from another country without overpaying for roaming?

Answer 2

With a number from one of our red provider with the letter "em" you can definitely - through the VoWiFi service. The call will come via WiFi, as if on a regular network, as if you were in your home region. The service itself is free.
Need phone support.

Answer 3

Any ip telephony like z adarma for forwarding.