That's a pretty big title for a blog entry, but it raises a few good points. Here's the top five reasons.
I've written a white paper, from which the following prose has been extracted (from the draft):
1. SIP is simple.
Using the great Internet Engineering Task Force fundamentals of technology reuse, and simplicity where simplicity is useful, the SIP message set is quite elegant. There are six messages that appear in clear text to facilitate all features. Clear text facilitates easy troubleshooting and avoids complex software interactions and other processing that affect interoperability. These six messages are:
- Invite
- Trying
- Ringing
- OK
- ACK
- Bye
This is practical since the base assumption is that all SIP endpoints and elements are surrounded by the Internet Protocol (IP) environment which is already equipped with standard mechanisms to handle packet transport priorities, privacy and other services as required. These value-added services do not require specification in the SIP framework, since they already exist and are available if the service and its specifications require it.
In legacy environments such as the public telephone network, these assumptions are not valid and the use of hyper-text transport protocol (http), for example are not assumed or readily available.
This ‘building block’ approach over IP is unique to any IETF initiative. The results are nearly trivial protocol definitions such as SIP in contrast with older session control or interface protocols such as H.323 or Q.sig from the International Telecommunications Union (ITU). These older, more telecom-centric protocols have more considerably more complex definitions.
In most endeavors of civilization and even in nature, simple is both useful and enduring. The sphere and its derivatives are frequently occurring shapes in fruit and celestial objects than say, the more complex pyramid, for example. The steering wheel gave way to the handle bar in automobile control designs, and the flat CD won over the more complex floppy disk cartridge design as the definitive media storage framework.
Years ago, a wise man once explained why Asynchronous Transfer Mode (ATM) was going to destroy a carrier service of interest to the phone companies at the time, called SMDS (Switched Multi-megabit Data Service which was a connectionless ATM-type service). There were two arguments: first of all, ATM was simpler (notice three-letter acronym versus the four-letter acronym) and secondly because you didn’t need to be a phone company to implement the technology – giving ATM a larger addressable market, which would provide ample opportunity to solve business problems.
