y'know... skype used to have this feature, y'know? it wasn't completely undetectable, but it *used* to have the ability to disguise itself as pretty much anything, so that it would "just work" in the face of badly-configured firewalls, DNS servers, idiot companies that blocked *all* incoming and outgoing traffic stone-dead including ICMP (including BGP and other absolutely crucial traffic) with the statement "you've got unrestricted access to port 80, that's the 'internet' isn't it, what the hell are you complaining about yer lame-techie-wannabe-tuck-fard??"
it also had the ability to create any kind of tunneling over pretty much any port and any protocol (TCP, UDP, you name it, it could do it) such that it was pretty much impossible to shut it down.
AND THEN.... for no good reason WHATSOEVER , skype changed hands not once but THREE TIMES in succession. now it's under the "control" of microsoft, and anyone considering installing it now is a fool. it's been turned into a "cloud is all" protocol. there's no peer-to-peer capability. that leaves it vulnerable to being mass-IP-range blocked. anyone can work out what the IP range(s) are of the various "cloud" servers used by microsoft are... and just block them (regardless of consequences).
so i *would* have said "just tell them to install skype". except we can logically deduce that it was SOME FUCKWIT IN THE U.S. GOVERMNENT who caused skype, in its current release, to lose its inherent firewall-busting capabilities to be COMPLETELY REMOVED.
and with skype being proprietary, and the "startup" (bootstrap) nodes no longer being run or "supported", we cannot even run older versions of skype any more because the older versions have been shut down. oh, and it's proprietary, so it would be man-decades before it is properly reverse-engineered. oh, and the original creators are likely to have been asked (or threatened) to enter into some serrrrious non-compete contract which, even if it wasn't legally enforceable, they probably understood the full implications were that if they wanted to keep all their body parts, they'd better like, y'know, not even *think* about writing a replacement / competitor, y'ken. they did try setting up a company called "joost", but interestingly, it "failed". i don't wonder why, not any more.
so, this appears to be a golden opportunity for software libre and proprietary software writers alike, but honestly it's a poisoned chalice. one department in the U.S. does *NOT* want such software to even *EXIST*... another is offering money to anyone willing to CREATE such software.... it's either a case of "left hand doesn't know what the right hand is doing", or it's just plain entrapment: the NSA wants to know if you have the CAPABILITY to write such software (and you're going to tell them who you are for god's sake!)
bottom line is, there's a phrase which covers this scenario in the security world - it's called "a honey pot". my advice to anyone who reads this: stay the FUCK away from this "offer" unless you're such a huge software libre team (over 100 people would do it) that it would be clearly obvious if one or more people suddenly "went missing", or "received sudden lucrative job offers" or "went on holiday" or "won the lottery" or "had an accident". what would *really* do it is if EVERYBODY who is capable of collaborating on this (including people from proprietary software companies) joined *ONE* single software libre team (with a single person allocated as the front-man), where everybody else used anonymous two-way communications with that front-man), and through them proposed one single entry for the "competition". 100, 200, 300 people, the more the better. if the application *requires* that every single person on the "team" be named individually and separately (either before or after the application), then you can logically deduce that it's extremely likely to be a honeypot. if the application's mysteriously "denied" when there's only the one entry, you can logically deduce that it's extremely likely that the exercise was a honeypot.
 when you see 3 companies in a row throwing of the order of magnitude of a billion dollars at a single company for a single piece of software with such a limited use-case (chat, voice, video), you cannot possibly expect anyone to believe that they're each doing so because it's "financially justified". the logical conclusion is that there was some other factor involved... such as HEY WE'RE THE NSA, WE'LL GIVE YOU LOTS OF EXTRA BUSINESS IF YOU GET THAT SOURCE CODE AND GIVE US A COPY. remember: the original creators of skype were extremely clever, and utterly paranoid: they let NOBODY see the source code. back when it was initially created, the core library was ONLY made available in BINARY form EVEN to the GUI front-end developers(!) and it had a "protection" mechanism where it could detect that it was running under a Virtual Machine, detect if it was being "debugged" (single-stepped), and it would self-destruct and shut down automatically. the NSA even offered a million dollars to anyone who was willing to "break skype". yes, really, that's a matter of public record! nobody managed it. all the "social engineering" tricks and presumably various trojans that are normally successfully used to perform industrial espionage presumably failed... so they had to go to the drastic lengths of actually inducing some lame-fool company to buy the ENTIRE company. for a billion dollars. well done the founders of skype is all i can say!