I’ve had quite a few mails since my article for the TechNet newsletter went out yesterday (and blog post earlier today). There’s obviously lots of interest about VOIP as I’ve had various mails ranging from how to set up a PBX, questions for information on case studies, queries on how to become more involved with us as we launch OCS 2007 later on this year, and a mail from someone asking if he could come and work in the team (where were you when I was recruiting 2 months ago?!). But the one which made me stop and think was the mail asking why I didn’t write about a comparison with Skype. As I was answering the mail, I realised that it may be worth talking about the differences here. If you’re new to OCS 2007 or don’t have enough information to make a comparison between the two, there’s a good webcast here by the way as well as many other resources linked to from the home page.
Skype is a peer to peer decentralised system. OCS voice maintains call routing inside of the company until the gateway dials the number (if the recipient is outside of the company). With a decentralised system the potential for anyone to sniff (intercept) the call is much much greater.
“Skype uses a design called a “supernode P2P architecture”, over which all Skype communications are handled. Rather than rely on a single big central server to complete calls, Skype software clients directly interact with each other to ensure that the network directory is up to date and that calls are quickly completed.” (From the Admin guide). This means that your client PC is used to relay calls to other Skype users. Think of the processor overhead..
Skype decides how it routes the call. Skype may conclude that the most effective way to route a communication is not directly between the called and calling endpoints, but instead to send the traffic via another Skype client not otherwise involved in the call.
Networks with super-nodes may experience large flows of inbound and outbound traffic that have no connection with any local user. A user who installs Skype with the default configuration permits his computer and his organisation’s bandwidth to be used by any other Skype user (See JANET documentation)
The current End-User Licence Agreement for Skype located here says:
“You hereby acknowledge that the Skype Software may utilize the processor and bandwidth of the computer (or other applicable device) you are utilizing, for the limited purpose of facilitating the communication between Skype Software users”
So you’re paying for others to use “your” bandwidth to make calls.
Security:
Skype effectively provides an encrypted tunnel through the firewall that could be used for attacks against the client PC and any other networked devices it can connect to in turn. This also means that any filtering or protection for the user or their PC that is implemented on the organisation’s firewall or network will be unable to inspect files or other content transferred to the Skype client. (again from the JANET docs)
Not good for security then, and it seems it’s also possible to reverse engineer the protocol too.
So that’s why I didn’t do a comparison when I wrote the piece for the TechNet newsletter. OCS 2007 is a completely different animal that uses the infrastructure inside your organisation to route calls. the client PC’s aren’t used to assist with the calls (just to answer them of course).
No contest really…
Eileen's Digital Technology 