As a practical point, saying it in English will almost certainly communicate what you need to communicate. Almost everyone who makes international calls will recognize that you’re speaking English even if they don’t understand what you’re saying, which suggests that the Russian or Korean speaking person they’re trying to reach is not at that number.
There was a recent related discussion on Hacker News and the top comment discusses why this sort of solution is not likely to be the best fit for smaller organizations. In short, doing it well requires time and effort from someone technically sophisticated, who must do more than the bare minimum for good results, as you just learned.
Even then, it’s likely to be less reliable than solutions hosted by big corporations and when there’s a problem, it’s your problem. I don’t want to discourage you, but understand what you’re committing to and make sure you have adequate buy-in in your organization.