If the mailbox is NOT setup, the fixed system message, "I'm sorry�" followed by the mailbox number and "�is currently on the phone" plays instead of the mailbox name and personal greeting.
The importance of voicemail in the customer care sector has not diminished despite the arrival of newer web technologies. VoIP applications let the businesses use voicemail service with flexibility, as it is. The users need not rely on extension terminals when they use VoIP services. A strong internet connection is a prerequisite and the pre-configured phones can be used – both for calling /receiving calls and for automated custom greetings. IVR feature redirect callers to the right virtual extension where their needs can be addressed. This can be done anywhere through a web portal access and an internet connection.

The basic rule of thumb is that callers should hear one of two things when they first connect with your voicemail — either an apology for not being able to answer the call or a “thank you” for having called. You can do both if you prefer, but keep it short and to the point.
The alternative is simple: Provide in your voice message a phone number and refer the caller to an assistant, a colleague, a cell number—any way of expediting their quest. Help your caller to reach someone who can, in your absence, be helpful and succeed in keeping the business. And remember to update your voicemail message when appropriate.