Each extension in a phone system is normally linked to a voice mailbox, so when the number is called and the line is not answered or is busy, the caller listens to a message previously recorded by the user. This message can give instructions to the caller to leave a voice message, or provide other available options. Options include paging the user or being transferred to another extension or a receptionist. Voicemail systems also provide notifications to users to inform them of new voicemails. Most modern voicemail systems provide multiple ways for user to check their voicemail including access through PC’s, mobile phones, landlines or even through SIP clients running on smartphones.