3. "Hey, this is [your name]. If you're calling for [X reason], please [contact so-and-so] or [go to our website, send me an email]. For all other inquiries, leave your name and a brief message and I'll call you back within [one, two, three] business day[s]."
A voicemail greeting script for an individual lawyer should be brief and encourage face-to-face meetings over phone tag. This allows you to interact with your client directly, and if you're a defense lawyer, it could keep your client from saying incriminating things over the phone. This is the voicemail of Ronald Smith, attorney at law.

Make sure to keep your voicemail greeting fresh and new. In fact, updating your voicemail regularly will ensure that people actually listen to your message. Anytime you are on vacation, at a conference or other industry-related event, change your greeting to reflect where you are at.
Expanding on the simple approach above, let the caller know who they've reached. This will not only eliminate people leaving voicemails by mistake, but it will reassure the caller that they have called the number they intended.