Will an Apple iPhone 4s bought in the USA work in Russia?

Question

iPhone

operator - Sprint.
clean ESN i.e. doesn't seem to be blocked

Answer 1

if the phone is not tied to an operator in the country of purchase, then it will work in other countries

Answer 2

If you did not conclude an agreement with the operator, then it will.
But 4g won't work

Answer 3

It will not work with Big Three networks (Beeline, Megafon and MTS). Sprint's networks, like Verizon's, operate on the CDMA standard. Only Skylink works on the same standard in Russia, and it’s not a fact that it is compatible with Sprint or Verizon.
If you want to work in the Russian Federation not only via Wifi, then take it from AT&T - they are a GSM operator.