This is a really good question. The answer at the moment is, no. But if you had asked just a few months ago, the answer would have been, it depends. The reason the answer is a lot clearer today is because of a number of court decisions declaring the law unconstitutional.
Before those decisions, Illinois had been notable as having one of the most stringent anti-eavesdropping laws in the country. It made it illegal to make any audio recording of a conversation, public or private, unless all the parties involved consented to it. The law was enacted in 1961. Under it, you could be charged with a Class 1 felony. Conviction could result in a 15-year prison term.
Many have long considered the law an overreach and a violation of the Constitutional protections of free speech because it banned recordings of police on the job, but it stood for decades.
In 2011, it resulted in a 20-year-old woman being tried. She had secretly recorded two officers she thought were trying to dissuade her from filing a complaint against another officer. She was acquitted, but many questioned whether she should ever have been charged in the first place.
In 2012, the U.S. Supreme Court weighed in on the issue. As was widely reported then, the court ruled in a suit brought by the American Civil Liberties Union that the law could not be used to prosecute individuals for making audio recordings of officers on duty.
Most recently, as recorded on the Illinois Supreme Court website, the law was declared unconstitutional because it banned not only private conversation recordings, but also outlawed recording of speech that is clearly public, such as fan noise at an athletic event or public debate. The justices used two cases to observe that the 1961 law was out of date with today's technology and too sweeping.
What this means for now is that the law is void. But the justices also suggested that the legislature pass a new bill to properly protect private conversations. So, we'll have to wait to see what develops next.