When you first use your voicemail service you will need to record your greetings and set a security code. To do this press the Message key on your phone. This will connected you to the voice mail system, when prompted enter the default security code. (The default security is available here. Requires Drexel credentials to view.) Then follow the prompts to record your greeting and to establish your security code. The security code is a numeric password used to prevent others from accessing your voicemail messages.
If you aren't performing your initial mailbox activation from your own University provided phone, please see instructions on how to access voicemail remotely.