SIP

Vol. 5 No. 2 – March 2007

SIP

Articles

Decentralizing SIP

If you're looking for a low-maintenance IP communications network, peer-to-peer SIP might be just the thing.
SIP (Session Initiation Protocol) is the most popular protocol for VoIP in use today. It is widely used by enterprises, consumers, and even carriers in the core of their networks. Since SIP is designed for establishing media sessions of any kind, it is also used for a variety of multimedia applications beyond VoIP, including IPTV, videoconferencing, and even collaborative video gaming.

Decentralizing SIP

If you're looking for a low-maintenance IP communications network, peer-to-peer SIP might be just the thing.

P2P SIP provides a low-maintenance alternative to more centralized SIP implementations.

David A. Bryan And Bruce B. Lowekamp, Sipeerior Technologies

SIP (Session Initiation Protocol) is the most popular protocol for VoIP in use today.1 It is widely used by enterprises, consumers, and even carriers in the core of their networks. Since SIP is designed for establishing media sessions of any kind, it is also used for a variety of multimedia applications beyond VoIP, including IPTV, videoconferencing, and even collaborative video gaming.

In the past three years, interest in decentralized, peer-to-peer SIP (P2PSIP) has increased. P2PSIP removes or reduces the number of centralized servers needed in a SIP deployment.2,3,4,5 There has been much speculation that this interest can be attributed to Skype, the popular pseudo-P2P communications service (Skype still tightly centralizes authentication, billing, and admission control). Although one potential use is to build a SIP-based, low-cost, server-less worldwide network, much of the interest has to do with enabling SIP to operate in deployments where conventional server-based SIP isn't well suited.

by David A. Bryan, Bruce B. Lowekamp

Making SIP Make Cents

P2P payments using SIP could enable new classes of applications and business models.
The Session Initiation Protocol (SIP) is used to set up realtime sessions in IP-based networks. These sessions might be for audio, video, or IM communications, or they might be used to relay presence information. SIP service providers are mainly focused on providing a service that copies that provided by the PSTN (public switched telephone network) or the PLMN (public land mobile network) to the Internet-based environment.

Making SIP Make Cents

P2P payments using SIP could enable new classes of micropayment applications and business models.

New micropayment systems might be just around the corner.

Jason Fischl, Counterpath, and Hannes Tschofenig, Siemens

The Session Initiation Protocol (SIP) is used to set up realtime sessions in IP-based networks.1 These sessions might be for audio, video, or IM communications, or they might be used to relay presence information. SIP service providers are mainly focused on providing a service that copies that provided by the PSTN (public switched telephone network) or the PLMN (public land mobile network) to the Internet-based environment.

Some advantages of using SIP for this purpose are:

by Jason Fischl, Hannes Tschofenig

SIP: Basics and Beyond

More than just a simple telephony application protocol, SIP is a framework for developing communications systems.
Chances are you're already using SIP (Session Initiation Protocol). It is one of the key innovations driving the current evolution of communications systems. Its first major use has been signaling in Internet telephony. Large carriers have been using SIP inside their networks for interconnect and trunking across long distances for several years. If you've made a long-distance call, part of that call probably used SIP.

SIP Basics and Beyond

More than just a simple telephony application protocol, SIP is a framework for developing communications systems.

What is SIP, and what is it good for?

Robert Sparks, Estacado Systems

Chances are you're already using SIP (Session Initiation Protocol). It is one of the key innovations driving the current evolution of communications systems. Its first major use has been signaling in Internet telephony. Large carriers have been using SIP inside their networks for interconnect and trunking across long distances for several years. If you've made a long-distance call, part of that call probably used SIP.

More recently, SIP has made it into the hands of the end user through a variety of devices that look and act a lot like telephones (but have only an Ethernet jack) and service providers such as Vonage that offer telephony over any existing Internet connection. The next generation of mobile phones will use SIP as the primary signaling technology. SIP's utility does not end with telephony: it is already employed as a basic technology for IM (instant messaging) and presence.

by Robert Sparks

Interviews

A Conversation with Cullen Jennings and Doug Wadkins

In our interview this month, Cisco Systems' Cullen Jennings offers this call to arms for SIP (Session Initiation Protocol): "The vendors need to get on with implementing the standards that are made, and the standards guys need to hurry up and finish their standards." And he would know. Jennings has spent his career both helping define IP telephony standards and developing products based on them. As a Distinguished Engineer in Cisco's Voice Technology Group, Jennings's current work focuses on VoIP, conferencing, security, and firewall and NAT traversal. His primary responsibility is setting the direction of the technology that will make up the next generation of Cisco's voice products, especially those concerned with conferencing, presence, and rich media systems.

A Conversation with Cullen Jennings and Doug Wadkins

Getting the lowdown on SIP

In our interview this month, Cisco Systems’ Cullen Jennings offers this call to arms for SIP (Session Initiation Protocol): “The vendors need to get on with implementing the standards that are made, and the standards guys need to hurry up and finish their standards.” And he would know. Jennings has spent his career both helping define IP telephony standards and developing products based on them. As a Distinguished Engineer in Cisco’s Voice Technology Group, Jennings’s current work focuses on VoIP, conferencing, security, and firewall and NAT traversal. His primary responsibility is setting the direction of the technology that will make up the next generation of Cisco’s voice products, especially those concerned with conferencing, presence, and rich media systems.

Jennings is also actively involved with the IETF (Internet Engineering Task Force), where he serves as realtime applications area director. In this role he leads the IETF’s activities involving voice, video, and instant messaging. Jennings also makes key contributions to all of the SIP security work at IETF. He was the original designer of SIP’s certificate management system and most recently was responsible for the SIP Identity RFC.

Kode Vicious

APIs with an Appetite

Dear KV, This may sound funny to you, but one of my co-workers recently called one of my designs fat. My project is to define a set of database APIs that will be used by all kinds of different front-end Web services to store and retrieve data. The problem is that a one-size-fits-all approach can't work because each customer of the system has different needs. Some are storing images, some are storing text, sound, video, and just about anything else you can imagine. In the current design each type of data has its own specific set of APIs to store, search, retrieve, and manipulate its own type of data. If I constrain the API too much, then some group won't be able to use it and will build its own local API. That means we will lose the advantages of having a central store for all different types of data. As it stands now, there are about 500 different API calls in the library. Is that too fat?

APIs with an Appetite

A koder with attitude, KV answers your questions. Miss Manners he ain’t.

Time for everyone’s favorite subject again: API design. This one just doesn’t get old, does it? Well, OK, maybe it does, but leave it to Kode Vicious to inject some fresh insight into this age-old programming challenge. This month KV turns the spotlight on the delicate art of API sizing. Have more API questions? Send them, along with any other coding queries, to kv@acmqueue.com. You’ll be glad you did.

by George Neville-Neil

Articles

Arm Your Applications for Bulletproof Deployment: A Conversation with Tom Spalthoff

The deployment of applications, updates, and patches is one of the most common - and risky - functions of any IT department. Deploying any application that isn't properly configured for distribution can disrupt or crash critical applications and cost companies dearly in lost productivity and help-desk expenses - and companies do it every day. In fact, Gartner reports that even after 10 years of experience, most companies cannot automatically deploy software with a success rate of 90 percent or better. In this ACM Premium Queuecast with host Mike Vizard, installation expert Tom Spalthoff from Macrovision discusses how companies can achieve a reliable desktop environment while reducing the time and cost spent preparing high-quality application packages that deploy successfully.

Arm your Applications for Bulletproof Deployment: A Conversation with Tom Spalthoff

Companies can achieve a reliable desktop environment while reducing the time and cost spent preparing high-quality application packages.

Queue: Hello, this is another edition of the ACM Queuecast Premium Edition with your Host, Mike Vizard. Joining me today is Tom Spalthoff, who's the Systems Engineer from Macrovision, the leading provider of application packaging solutions. Tom, welcome to the show.

Spalthoff: Thanks, Mike.

Curmudgeon

As Big as a Barn?

Taking measure of measurement
The Texas rancher is trying to impress the English farmer with the size of his property. "I can drive out at dawn across my land, and by sundown I still haven't reached my ranch's borders." The Englishman nods sympathetically and says, "Yes, yes, I know what you mean - I have a car like that, too."

As Big as a Barn?

Taking measure of measurement

Stan Kelly-Bootle, Author

The Texas rancher is trying to impress the English farmer with the size of his property. “I can drive out at dawn across my land, and by sundown I still haven’t reached my ranch’s borders.” The Englishman nods sympathetically and says, “Yes, yes, I know what you mean—I have a car like that, too.”

 A joke should seldom be subjected to explanatory dissection, but here I seek your indulgence. As with all but the most blood-crazed lepidopterists, a few thoraxes must be pinned and a few wings plucked—some butterflies, even the rarest Red Admirables,1 must pay the ultimate price in the cause of entomological advancement. The etherized joke has two obvious clichéd elements followed by an unexpected punch line. The stereotypical Texan boasting of ownership and size is always good for a cheap laugh in smaller, jealous states and nations. The proof of size, though, is not revealed in normal units of distance or area, but as the time taken to traverse the property. Since d = v x t (distance = velocity x time), the inference is that for a given constant v, the journey time, t, does in fact provide a reasonable, comparative unit for the distance d. This notion is suddenly overturned, however, by that annoyingly smug, modest, ironic, pipe-puffing Brit. The Texas hype is literally inverted: the equation is rewritten as t = d/v, and the implied reason it takes 12 hours to cross the ranch is not the huge, boastful value of d but the pathetically low value of v, the top speed of the car!

by Stan Kelly-Bootle

Articles

From Liability to Advantage: A Conversation with John Graham-Cumming and John Ousterhout

Software production (the back-end of software development, including tasks such as build, test, package and deploy) has become a bottleneck in many development organizations. In this interview Electric Cloud founder John Ousterhout explains how you can turn software production from a liability to a competitive advantage.

From Liability to Advantage: A Conversation with John Graham-Cumming and John Ousterhout

Software production has become a bottleneck in many development organizations.

Q: Welcome to this month's Queuecast, featuring conversation with John Graham-Cumming and John Ousterhout, cofounders of Electric Cloud, Inc. Electric Cloud produces solutions that automate, accelerate, and analyze the entire software production management process, and with that, I'll turn it over to John Graham-Cumming. John?

JOHN GRAHAM-CUMMING: Thanks very much. And we're here today to talk about something that Electric Cloud has really staked a claim to, and that is software production management. So, John, this is a new term. What is it all about?

Opinion

Repurposing Consumer Hardware

These days you have to be more and more creative when tackling home technology projects because the inventory of raw material second-hand technology is changing so rapidly. Market and product cycles continue to shrink, standard form factors are being discarded to drive down costs, and pricing is becoming more dependent on market value and less on direct manufacturing cost. As a result, standard modular building blocks are disappearing. New alternative uses for obsolete or low-price products are emerging, however. I enjoy finding ways to extract new value from new or used hardware platforms, so I think it's still a good time to be a technology hobbyist.

Repurposing Consumer Hardware

New uses for small form-factor, low-power machines

Mache Creeger, Emergent Technology Associates

These days you have to be more and more creative when tackling home technology projects because the inventory of raw material—second-hand technology—is changing so rapidly. Market and product cycles continue to shrink, standard form factors are being discarded to drive down costs, and pricing is becoming more dependent on market value and less on direct manufacturing cost. As a result, standard modular building blocks are disappearing. New alternative uses for obsolete or low-price products are emerging, however. I enjoy finding ways to extract new value from new or used hardware platforms, so I think it’s still a good time to be a technology hobbyist.

When I first started developing a home IT infrastructure, PCs in standard form factors were readily available in the used marketplace. AT and ATX enclosures were ubiquitous, and all that you had to do to create a home server was to collect the relevant used parts and install them in a second-hand box. That’s not so easy anymore. Notwithstanding that the majority of PCs sold today are laptops, most desktop systems are now being sold by Dell and HP and use proprietary form factors to reduce cost. Where I used to have my pick of second-hand desktop enclosures for servers, used standard form-factor boxes are getting harder and harder to find. Recently I was forced to perform the ultimate unnatural act of a hobbyist: I actually had to purchase a brand-new case. Shudder.

by Mache Creeger

Articles

Unified Communications with SIP

SIP can provide realtime communications as a network service.
Communications systems based on the SIP (Session Initiation Protocol) standard have come a long way over the past several years. SIP is now largely complete and covers even advanced telephony and multimedia features and feature interactions. Interoperability between solutions from different vendors is repeatedly demonstrated at events such as the SIPit (interoperability test) meetings organized by the SIP Forum, and several manufacturers have proven that proprietary extensions to the standard are no longer driven by technical needs but rather by commercial considerations.

Unified Communications with SIP

SIP can provide realtime communications as a network service.

MARTIN J. STEINMANN, PINGTEL

Communications systems based on the SIP (Session Initiation Protocol) standard have come a long way over the past several years. SIP is now largely complete and covers even advanced telephony and multimedia features and feature interactions. Interoperability between solutions from different vendors is repeatedly demonstrated at events such as the SIPit (interoperability test) meetings organized by the SIP Forum, and several manufacturers have proven that proprietary extensions to the standard are no longer driven by technical needs but rather by commercial considerations.

Even in light of all this excellent news, most implementations still fall short in one key area: native SIP call control and SIP-based feature interaction required for multivendor interoperability. SIP first unfolds its full potential if it is used for more than just transport “channels” that interconnect otherwise proprietary IP PBX implementations. The simple fact that SIP “goes in” and “comes out” of a PBX system does not mean that this system has much to do with SIP at all. Native SIP call control and SIP transport “channels” are two very different and oft-confused architectural approaches to building SIP communications systems.

by Martin J. Steinmann

Interviews

Bringing IT All Together

A piecemeal approach to building data centers that relies on commodity servers, switches and systems management software only leads to inefficient systems that add unnecessary cost and management overhead to IT operations. In an interview with Queuecast host Mike Vizard, Liquid Computing CTO and co-founder Mike Kemp offers a fresh approach to enterprise computing.

A piecemeal approach to building data centers that relies on commodity servers, switches and systems management software only leads to inefficient systems that add unnecessary cost and management overhead to IT operations. In an interview with Queuecast host Mike Vizard, Liquid Computing CTO and co-founder Mike Kemp offers a fresh approach to enterprise computing.