DIY Cell Phone Reception Booster

Ever walked in urban canyons while talking on your cellphone, only to be cut off in mid-coversation due to the lack of signal strength? If you are a fan of a little DIY project, there's this cellphone reception booster exercise that you can indulge in which actually seems to work far better than commercially obtainable solutions (which I think are a scam). I'd try this with an elderly handset first if I were you for a trial run before hacking a new mobile phone.