Verified answer

Si te lo escribo en español es más fácil.

Cuando introdujeron los teléfonos a México, la recepción no era muy buena. No llamabas directamente a cualquier número como haces ahora, llamabas a una operadora para te comunicara con el número que al quisieras comunicarte, la operadora contestaba el teléfono "¿bueno?" para saber si la recepción era buena y podía conectarte, si así era entonces tú respondías "bueno". De ahí surgió la costumbre de responder el teléfono con bueno. Esto sólo es en México, en otros países de habla hispana se responde con ¿hola?, ¿diga?, etc. Aunque la historia es parecida en Italia con "pronto".

I did a little research on this a while back.

It implies, "Yes?".

Apparently, at least according to what I read, "¿bueno?" referred to the phone connection, implying, "is the connection good", "can you hear me o.k.?". So that phrase stuck, and instead of asking the entire question, it was shortened to "¿bueno?". It is like some say, "thank you", and now we say "thanks".

Remember the t.v. famous Verizon cell phone commercial, and a guy asking, "Can you hear me now?"

It talked about bad signals, and poor connections.

It is an upbeat or nicer way of saying "Yes?". It is almost like a slang (but not really) and exception word greeting, because Bueno does not really mean yes.

Us spanish speakers answer the phone with "Buenas" because it is a greeting just like in america you guess say "hello"

"Bueno?" could also be used as "Well?"

Every culture has a somewhat different phone call answering phrase, so the reason is simply a cultural one

If i don't be attentive to who's looking, I say "¿sí?" (confident) or "dígame". it is what maximum folk say in Spain. If i be attentive to who's calling I say "hola" (hi) If i'm at artwork I say "buenos días - buenas tardes" (stable morning - afternoon)

But this is in Latin America

In Spain we don't say that.

We say. ¿Si? ¿Diga? .. etc