Consider for a moment how your phone is currently being answered. Professional courtesy is quite often not the standard for many college students. An abrupt "Yeah!" could be listed among the more courteous greetings. The more outrageous remarks will often buy you a major black mark in the professionalism category—even if it was your roommate answering your phone and acting crazy. A simple "This is ____" is always a pleasant change for a college student call. Make the change today, before the next (or first) employer phone call. If you have a landline, you should also encourage your roommate to do the same.
Cell phone voicemail greetings are generally more personal and casual than office phones. Consider a greeting like “Hello, you’ve reached [your name]’s cell phone. I can’t take your call at the moment, but if you leave a brief message, I’ll get back to you as quickly as possible.”

There is no definitive answer here, but you should include one of the two at the beginning of your message based on what makes the most sense.
No, the voice mail on your phone can only be deleted through your Cox Business voice service or a cell phone. We recommend that you delete all audio files after listening to them since these files are large and will decrease your email storage capacity. (Note: Voice Mail older than 31 days will automatically be deleted from the mailbox.) The voice mail message can be transcribed up to 90 seconds. You can call your voice mail number or play the .wav file to listen to the entire message. I checked the box to receive Text (or audio) but did not get the email. What happened?