Usually a combination of a low pass filter quite high up the low-midrange, and a high pass filter around 8kHz ish, and then adding a bit of distortion to taste if you like... it's the same kind of frequency bandwidth utilised by a telephone, hence how you recognise the tone, and should be quite achievable with a bit of messing around but if not there are surely tons of telephone-emulators on google? I know Speakerbox features some, and Logic comes bundled with effects like this (as I've used one before to simulate a phone conversation on a project for someone).
Hey, look. Sigs are back.
If you don't want to start from scratch then open up an EQ in your daw and there might be some presets already there that sound similar and can guide you in the right direction.
^ Both of the posts above. I always start with Presets then adjust to my liking. Also awesome choice of music!

Theres a preset on Cubase which sounds alot like it. I don't think theres any distortion on it becuase the spike in high mids make it sound distorted. Heres a pic:

Last edited by Afroboy267 at Mar 26, 2011,