You may have heard about the voicemail hacking that reportedly took place in the 2011 UK News International hacking scandal. Before the scandal, you rarely heard the terms voicemail and hacking in the same sentence. One thing that came out of this scandal was that it made many people think about how insecure their voicemail accounts could be.

Most voicemail accounts are secured with a simple 4-digit access code. Voicemail is typically accessed from a telephone, so the access code can only consist of numeric digits. A numeric access code combined with a 4-digit PIN reduces the total number of possible combinations to just 10,000. This may seem like a long time for someone to try, but in reality it can be done in less than a day or two, or even faster if you are using a computer with a modem and a scripted autodialer program.

Some people don't even bother to change their PIN/access code from the default. In many cases, the default is the last four digits of the phone number or something as simple as "0000," "1234" or "1111."

The harsh reality is that until the complexity of voicemail passwords is on par with the authentication methods used by other types of networks, voicemail will remain vulnerable to hackers and can be easily compromised.