How voicemail solved the business communication problem

Voice mail’s introduction enabled people to leave lengthy, secure and detailed messages in natural voice, working hand-in-hand with corporate phone systems. The adoption of voicemail in corporations improved the flow of communications and saved huge amounts of money. GE, one of the pioneer adopters of voicemail in all of its offices around the world, claimed that voicemail saved, on average, over US$1,100 per year per employee.

Voicemail has two main modes of operation: telephone answering and voice messaging. Telephone answering mode answers outside calls and takes a message from any outside caller (either because the extension was busy or rang no-answer). Voice messaging enables any subscriber (someone with a mailbox number) to send messages directly to any or many subscribers’ mailboxes without first calling them. Both of these modes are described below.

Telephone answering mode

One of the advantages of a PBX is its ability to forward calls. If a person is using his phone or does not answer it, calls to his extension are forwarded automatically by the PBX to another extension, presumably someone (like a secretary) who can answer the call and take a message. With a voicemail system installed, the PBX is programmed to forward busy or unanswered extensions to a machine — the voicemail system.

Suppose an outside caller, Willma, calls someone in a company, Fred. If Fred’s phone rings "no answer" or "busy", the PBX will forward the call to the voicemail system. Somehow the PBX needs to tell the voicemail system that Fred’s phone is the one that the call is being forwarded to so that the voicemail system can answer with Fred’s personal greeting. Without this information, the voicemail system would have no idea whose phone it was answering. Once a message is left, the voicemail system illuminates the message waiting light on Fred’s phone. It does this by sending a signal to the PBX to tell it which light to light. When Fred returns to his desk and calls the voicemail system (or calls in remotely) he is presented only with the messages in his personal mailbox even though thousands of messages belonging to other people are stored on the same system. Once the messages are played, the voicemail system signals the PBX to turn off the message waiting light on Fred’s phone.

Early voicemail systems (notably those made by IBM and VMX) could not answer outside calls — that is, they could not automatically answer a call originally destined to an extension on the PBX which rang busy or was not answered. As subsequent voicemail systems emerged (notably ROLM and Octel which later merged with Boston Technology), the systems could answer outside calls. However, most PBX’s did not provide signaling to tell the voicemail system which extension it was forwarding, nor did they support telephones with message waiting lights. This signaling would come later, but until it did it created a major challenge for voicemail systems for many years.

Voice messaging

This mode is to phones what email is to computers. Messages are sent to other users by calling the voicemail system rather than the user’s phone. For example, suppose two employees, Fred and Mary, are working on a project. Fred has some information that Mary should have, but does not want to phone her and talk to her — he just wants to give her the information. Rather than phone her, Fred calls the voicemail system, logs on with his number and password, and records a message to Mary in his own voice. He tells the voicemail system to send it to Mary by keying in her mailbox number (same as her extension) or spelling her name using Touch-tone keys. The message is immediately put in Mary’s voice mailbox without her phone ever ringing. The message waiting light on her phone immediately comes on telling her there is a message. Fred can send this message just to Mary, to Mary and any number of additional employees, or to group lists which contain any number of pre-programmed names and numbers. The same message can be sent to thousands of people. Additional features are available, like marking a message urgent, private or asking for notification when the message has been picked up.

Interoperability between systems

Voice messaging does not always have to be sent between individuals on the same voicemail system. Messages can be transferred using AMIS (Audio Messaging Interchange Specification) or VOIP (Voice Over Internet Protocol) technologies; both allow messages on one computer system to be forwarded to the target system. Like email, this method of delivering voice messages can be subject to abuse such as spam or vishing. There are Federal and State laws and regulations designed curb these abuses, such as the United States National Do Not Call Registry.