The reasoning was simple: Symbian offered a ready-made product that would help Sony ship millions of units per week. And no one else offers a similar product.
Sony -- which said its wireless phone is expected within the year -- was the first major phone manufacturer to announce such plans.
Symbian, developed by a consortium grouping Psion with mobile phone makers Nokia, Ericsson and Motorola, uses an EPOC-based Pearl operating system. It is specifically designed for smartphones, the next big trend in the cellular phone market, which ships approximately 10 million units per week.
Rivals Palm (palm) and Microsoft (msft) have been focusing their attention on the PDA market, which has shipped about 20 million units -- total -- thus far. Their operating systems can be used for phones, but they aren't streamlined for phones.
"The agreement is an indication that Symbian is starting to bear itself out as the most efficient and best fit OS for wireless handsets. Its key feature is its scalability, which allows it to be used in devices of all flavors," said Bryan Prohm, senior analyst at Dataquest.
"Palm is more of a PDA-specific OS," said Sony's Mack Araki, explaining why his company chose Symbian over its rivals.
Microsoft, meanwhile, has focused on an end-to-end wireless strategy to this point, supporting everything from clients, services, and servers.
But that should change starting later this year, when Microsoft will announce support for feature phones, units optimized for online browsing; and continuing next year with support for smartphones, units with PIM capabilities that can be used online and offline.
Symbian's smartphone OS features include a voice-oriented interface, WAP and e-mail capabilities, security, and support for multimedia applications, said a company spokesman.
The company isn't ignoring the rest of the PDA market, though.
Other versions of the OS -- Quartz and Crystal -- specifically address handheld and palm-size devices.
The interfaces of the three versions are specific to the type of the device, but all have a slant toward wireless integration.