How do you get into tin tower on Pokemon Crystal?

Once you have beaten team rocket when they try to take over the radio tower, go to Ecruteak City and at the top of the town there is a place that looks sort of like a house, if you walk all the way up there is usually a bald man blocking your way. Talk to him and he will say you cannot be let through then after you show him the clear bell he will let you through. Simple :)