Voicemail is a service that records callers' voice messages when you cannot answer the phone. For landlines, it is provided as a recording function built into the phone unit, while for mobile phones, it operates as a network-based service from the carrier.
Mobile voicemail services can record messages on the network side even when the device is powered off or out of range - a major difference from landline answering machines. Recorded messages are typically played back by dialing 1417. Retention periods vary by carrier: NTT Docomo retains for up to 72 hours, au for up to 1 week.
Regarding fees, Docomo's voicemail service costs 330 yen/month, au charges 330 yen/month (included in the Phone Basic Pack), and SoftBank includes it free with some plans. Call charges also apply when playing back messages, so frequent users should be mindful of costs.
Recently, more people are using "Incoming Call Notification" services (free) that notify via SMS instead of voicemail. Features like iPhone's Visual Voicemail that display messages in a list for selective playback, and automatic voice-to-text transcription have also emerged. For nuisance call prevention, setting a short ring time before voicemail activates and having callers leave messages is an effective way to verify caller intent. Bank transfer fraud criminals tend to avoid being recorded, so voicemail activation alone serves as a deterrent. Police recommend "always-on voicemail" for elderly households, and some municipalities offer purchase subsidies for phones with automatic recording features. Review voicemail usage in how to handle unknown calls.