Top message: Lack of Quad-Band GSM phones by bones boy
Replying to: Re: Lack of Quad-Band GSM phones by gargspy
It's not so much extra components or software - that's the easy part.
For most manufacturers, it's all about antenna design. With a typical tri-band antenna, it's essentially just three pieces of connected metal. Each of the three pieces is a different "length", so it is "tuned" to that band, and that's how one piece of stamped metal can tune to three different bands at once.
But with quad-band, 900 is just too close to 850. If you try to tune it with two elements, they're too close in "length", and it doesn't work well. If you try it with one common element, it won't work well at the upper end of 900 or the lower end of 850.
So basically, it's hard to design an antenna that works well at both 850 and 900.
Now, Motorola seems to have the antenna part down, so the next question is why doesn't Motorola make all their phones quad-band?
The answer is that they do... They now make pretty much all of their GSM phones with quad-band radios and sometimes even antennas.
The reason they sell them as tri-band is mostly what gargspy said. They can offer the phone to a specific carrier faster and cheaper if they only have to optimize and test it for three bands instead of four.
It's not a small- nickel-and-dime thing... that extra testing and tweaking for the fourth band can add up to real money and a month or more of delays.