Is SIP Living up to its Potential?

We all know about SIP, and it's hard to deny its impact on IP communications, especially VoIP. Well, fellow blogger Brough Turner had a very thought-provoking post the other day that takes the contrarian view about SIP.

Brough's post actually ran last Friday, but it's taken me til now to get around to sharing this with you here. As you probably know, I'm not a news-hound, and there's nothing time-senstive about this post, so you're not missing anything if you're just reading about it now.

I can't comment much on the technical merits or shortcomings of SIP, but Brough certainly can. He makes some interesting points, two of which stand out for me....

1. Skype chose to use a proprietary protocol instead of SIP, and has proven by far to be the most popular web-based voice/IM application we've ever seen. It's conventional wisdom to knock Skype for being a walled garden that won't integrate with the other IM platforms, but when it comes to VoIP, Skype has proven its ability scale better than anyone. I guess this begs the question - could Skype have been as successful (let's leave profitability aside here) if they had used SIP instead? Would love to hear your thoughts on this one.

2. SIP's openness is somewhat contrary to the centralized nature of IMS. I get what Brough is saying here, but he didn't elaborate - and I wish he would - this contention needs some air.

Anyhow, Brough concludes that the best hope for SIP is peer-to-peer, and refers to an IETF working group for more detail. He may well be right, and some of the comments to his post are in agreement.

On the other side of the ledger is the SIP Forum, who will readily cite all the advances being made with SIP, especially with their SIPconnect Technical Recommendation, and ongoing SIPit interop events. I'd love to get a dialog going between these two parties, and just might push this along a bit. My partner in our IP Communications Insights venture, Marc Robins, serves as the SIP Forum's Executive Director, so I'll see if there's interest.

On a community level, I'd like to add that that Brough is a recent contributor to the IP Convergence TV portal, which I'm the Editor for. His article isn't about SIP, but it's a good read nonetheless. However, if you spend some time there, you will find some good SIP-related content from other contributors. Hope you come visit.

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Just FYI: Skype is profitable.

And... SIP is great. We use it everywhere we connect to the PSTN. We could not have been successful and profitable without something like this [i.e. a broadly adopted IP-TDM signaling interface].

Posted by: Jonathan Christensen at June 8, 2008 02:43 PM

Jon, not sure why you want to leave Skype profitability aside. According to eBay's last five quarterly reports, Skype has been a profitable division of eBay. (Just not as profitable as they may have liked re certain earnout terms on the Skype acquisition but that is a separate issue.)

Whatever their proprietary protocol, Skype has overcome NAT and firewall issues with great success as evidenced by its execution of completing calls, so with 30 or 40 million users online daily, they have to be doing something right.

Also of note:: Skype is one of the largest users of SIP for their SkypeIn and SkypeOut services. They leverage SIP for its one main feature at this time: the ability to interconnect voice conversations.

Posted by: Jim Courtney at June 8, 2008 03:42 PM