[asterisk-users] building a phone

[Jon Pounder]

Wilton Helm wrote:
> >Again, the main reason for me to require a higher end CPU is audio
> >compression. But I also want the system to be run by a standard OS. It
> >needs to be easy to add your own application there.
>  
> Mutually exclusive.  I don't know any standard OS that doesn't waste 
> about 10 x as many CPU cycles as a SIP phone should ever need.  The 
> problem is generalization.  A standard OS is designed to support a 
> wide variety of devices, including a wide range of screen sizes.  The 
> abstraction layers that make this possible often consume more CPU 
> resources than the application they are supporting.  Most of that 
> isn't needed for this application.  Compatibility with WXVGA isn't 
> required.  Even a full blown file system is a luxury.

This is not entirely true - many of the nokia phones use a java OS as a 
core, and you can load pretty much any java software you want on them, 
but all the points about power and battery use are still valid. (and 
whether you really consider that truly an OS is questionable, but its 
out there)



>  
> Linux is about the closest thing because it can be pared down.  But it 
> takes someone with considerable experience to know how and what to 
> trim.  I supervised a system that used "busy box" to create a compact 
> system that lived on a small flash card an some RAM.
>  
> As an example, I have been a Palm owner for a number of years.  I 
> laughed when the Win CE stuff came out to compete.  The Palm OS was 
> written for the task at hand.  I could go a week or more on a charge.  
> The Win CE devices had to be recharged after 8 hours!  Why?  The OS 
> required too much which required far more compute power, which ate 
> batteries.
>  
> The SIP phone you propose could be done with about 1 W of power plus a 
> couple more for backlighting.  An OS based version would start at 5 W 
> + backlight and could easily go to 15 W or higher.  Not the end of the 
> world, I suppose on a desk (if there aren't a hundred of them and I'm 
> not paying the electric bill) but a huge difference if it has to run 
> on batteries.
>  
> Wilton
>  
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