Thanks for contacting TextNow Support!
TextNow is unable to call Russian carriers at the moment. We're always working on adding more carriers for international calling and texting, and in fact you can text Russian numbers on the UTEL and Mobile Comms Systems carriers. (See our International Texting article, here: https://supportfree.textnow.com/hc/en-us/articles/203392669-International-Messaging)
Hope that helps!