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April 2008 | Volume 11/ Number 4
Ask the Mobile VoIP Expert

The History of SIP and Security in Mobile Multimedia Content

Many people believe that the Session Initiation Protocol (News - Alert), (SIP) is just a VoIP protocol. The impending migration to Mobile VoIP also depends on SIP. It was actually developed by a group of computer science students to monitor and report back the contents of their dorm room vending machines. The first papers directed the protocol toward its use for conferencing systems. The first Internet VoIP gateways designed for multi-party conferences were developed by a Denver-based firm, Confertech, in 1996. The team had high hopes for using the multicast backbone, or “M-Bone”, to save on bandwidth.

I recall one of our engineers, Bobby Mahonty, came across a published paper by Henning Schulzrinne (News - Alert) outlining the protocol as a multi-party multimedia session control solution. We had been working closely with Ike Elliot and the Level 3 team to form an industry alliance and the creation of standards for a “SoftSwitch”. Our team quickly rewrote the document and resubmitted it, referenced as SIP “Plus”, with the intent to replace our already maturing text based-protocols for our SoftSwitch. We also addressed in this draft the need for a security model much like HTTPS. The teams collaborated and actually built a reference design leveraging the early DNS concept behind FreeS/WAN, a project started back in 1996 to protect Internet traffic from passive wiretapping.

SIP is far more than a protocol for voice communications, as it was designed with multimedia in mind, and today, it’s beginning to emerge as a framework for any broadband service that produces a value or contains content. Standards and methods are finally beginning to reemerge after more than a decade of industry conflict. Security methods are needed now more than ever as we see the proliferation of common tools enabling novices to monitor and record SIP traffic from any layer 2 access point on a network.

Consumers may not be aware of the ease of these methods; however, the first time a CEO’s conversation is played back over a “blog”, the confidence in broadband communications will be shaken.

SIPS, sometimes referred to as Secure SIP, is a standards track that is easy to follow to build products and services. Although FreeS/WAN never really caught on, ENUM has since emerged from DNS standards and may have high value for the convergence of broadband services.

Next month I will address DNS and ENUM services and the critical role they play in providing ubiquitous and secure services to the final legs of convergence in broadband content and services.


History of FreeS/WAN:

SIPS Draft:

History of ENUM: IT

Mark Hewitt is Chief Strategic Officer of i2Telecom (News - Alert) International, Inc. (

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