A:AnswerIt just shows you the number of messages you have in the display on the base charging unit. For exap[me, if you have 2 new messages, it shows a red 2. If you have 0 messages, it shows a red 0. No audible sounds.
A:AnswerNo. This is a cordless phone for either VOIP or landline service. It can be paired to a cell phone, I believe, so you can use it as a handset, but it will not work exclusively with a mobile carrier.