I love my Poochie bells! My yogi never had to be trained on them, he figured them out his 2nd day. My other dogs never ring them...they just pester him till he does. Gotta say though, Jillian will ring them if he's slow to respond.
Some negative feedback I have seen on this site, is they figure out really quick how to use them just for fun & to train you to let them out when they don't have to go. My Yogi did this too....but I have come to learn the difference between the "I gotta go ring...with the half-hearted I just wanna play outside ring, or the "I hear a kitty out there, lemme out!" ring.
I have a fenced in yard, so the 4-5 times a day he rings the bell he is allowed out. But again he went through the phase that others have complained about...he rang the bell every 10 mins! Get through that phase, & you will love em too.