Assume for a moment, that a person in the US would call ISIS's headquarter "hot line" and say something like: "You know, I noticed some military guys are leaving the basis nearby and moving somewhere. Be aware of that, maybe this information will save lives of some jihad fighters!"
What do you think the FBI's reaction to that would be? (Regardless of the fact that the US troops are actually not planning at this moment a ground operation against ISIS.)
As a side note, that woman is no good spy. I mean, calling the open phone line of ANY EMBASSY (be it an embassy of Kazahstan, Belarus, Japan, China, the UK, or Antarctic Penguins') and thinking that line is not monitored by the Russian security is worse than naivette - it is either absolute stupidity or a public gesture - to become a 'prisoner of consciousness' or something like that. So, I think what the FSB is doing is sending everybody a message that this behaviour is a no-no, otherwise the ignorance in this case might cause other instances which might, actually, be harmful to the state. So, will this woman be released? I think yes, eventually, but she will spend quite some time in prison even before the court hearings to teach everybody a lesson that 'the FSB is not asleep, so mind what you're doing'. IMHO.