There is a far easier way to construct a red box that doesn't require much knowledge of circuit board construction or soldering.

1. Buy a Radio Shack (model 43-139) pocket phone dialer
2. Open it up
3. Replace the crystal (the silver tube-looking thing) with a 6.5536 Mhz. crystal. This will require soldering two connections. Deal.
4. Close it up
5. Save into memory five * (star) tones
6. Viola.

Or if you own a gameboy you can purchase a red box emulation cartridge on the net.

The red box still works, unlike it's blue box breathren, because the payphone systems are still basically the same as they've always been. The only way the telco knows that you've put your money in is through a tone that's sent over the phone line. Newer payphones disable the mouthpiece, which is actually a good solution, but one that hasn't been implemented very much. The advent of ESS effectively spelled the end of 2600 Hz. phreaking, but red boxing is still going strong -- probably the reason Radio Shack still sells the pocket phone dialers.