Unified Voicemail is the combination of different voicemail

Voicemail

Voicemail is a computer based system that allows users and subscribers to exchange personal voice messages; to select and deliver voice information; and to process transactions relating to individuals, organizations, products and services, using an ordinary telephone...

 bearers into a single voicemail system. Using dedicated DID

Direct Inward Dialing

Direct inward dialing , also called direct dial-in in Europe and Oceania, is a feature offered by telephone companies for use with their customers' private branch exchange systems...

 /DDI numbers for each mailbox, the mailbox can be used on a variety of devices and end-points. This is similar to what GSM providers use for their voicemail systems. Mobile phones and traditional analog phones need to support conditional call diversion to enjoy unified voicemail. Unified Voicemail can be extended into traditional unified messaging

Unified messaging

Unified Messaging is the integration of different electronic messaging and communications media technologies into a single interface, accessible from a variety of different devices....

.

Advantages of Unified Voicemail

Unified voicemails have emerged in importance in the last decade or so when consumers have adopted multiple platforms for their communication needs. An average consumer may answer to as many as four or five phone numbers, a traditional phone line at home, in the office, a mobile phone and a SIP number for his/her computer. With unified voicemail users can have one voice mail for all these disparate lines. They need to access a single mailbox, regardless whether the message has been left on their desk, mobile or VoIP phone.

Providers

• Alcatel
  Alcatel
  Alcatel Mobile Phones is a brand of mobile handsets. It was established in 2004 as a joint venture between Alcatel-Lucent of France and TCL Communication of China....
  
   - provider of Unified Communication solutions to enterprises in a comprehensive suite of services.
• Avaya
  Avaya
  Avaya Inc. is a privately held computer networking, information technology and telecommunications company that is a global provider of business communications systems. The international head quarters is in Basking Ridge, New Jersey, United States...
  
   - provider of communication systems, applications, and services.
• Cisco
  Cisco
  Cisco may refer to:Companies:*Cisco Systems, a computer networking company* Certis CISCO, corporatised entity of the former Commercial and Industrial Security Corporation in Singapore...
  
   - a vendor of Unified Messaging / Telecommunications for corporate use.
• CTL
  CTL
  CTL can refer to:*Computation tree logic*Cut-to-length logging*Complex Text Layout languages*cytotoxic T cell *Commission de transport de la Ville de Laval...
  
  - a manufacturer of unified desktop messaging solutions.
• NET - Advanced Gateway solution for enterprises that want to integrate Microsoft's Unified Messaging into their existing voice networks and legacy PBX systems.
• Nortel
  Nortel
  Nortel Networks Corporation, formerly known as Northern Telecom Limited and sometimes known simply as Nortel, was a multinational telecommunications equipment manufacturer headquartered in Mississauga, Ontario, Canada...
  
  - leader in Unified Communication.
• Taridium - vendor of Unified Messaging and Unified Voicemail solutions for the enterprise
• VoxCentral - provider of Unified Voicemail solutions for mobile-centric consumers and business users.