It's called Kiki's delivery Service and its a phone in thing. It started at the bakery and she uses the bakery phone. The worker at the baker makes kiki a sign so people whould notice it and phone in.
Kiki starts a self-titled delivery service in the town she settles in to begin her witch training. Kiki's delivery service is born after Kiki help's a pregnant bakery owner/service attendant return a pacifer to a customer whose baby drops it in the bakery. Kiki finds the bakery owner calling out to the customer unsuccessfully, so she offers to fly the pacifer back to the customer using her broomstick. A friendship is formed between the bakery owner and Kiki, and Kiki takes a room upstairs from the bakery to stay in. Kiki realises she can run her own business delivering things on her broomstick, at the same time as gaining much-needed flying experience. Customers are sought from the bakery below where a sign advertising Kiki's business is placed in the window, and the bakery owner offers Kiki the use of the bakery's telephone to arrange orders.