I think he's just saying that he's always waiting for her to come around - even if he's off doing something else (such as when people behind the counter are busy with something else & someone rings the service bell) he's still waiting to hear the sound of that bell that signals her coming back.
I think he's just saying that he's always waiting for her to come around - even if he's off doing something else (such as when people behind the counter are busy with something else & someone rings the service bell) he's still waiting to hear the sound of that bell that signals her coming back.