Lately I've noticed a series of calls coming in to my GrandCentral number from off shore. The people call at odd hours or worse when I'm sleeping. Since I rarely turn off my cell phones or soft clients where agency client GrandCentral is routing calls to I am thrilled at the ease of one click and send them to voice mail that GrandCentral lets me do. I do the same with my Webley number via a rule so between the two, I'm not reachable when I don't want, or need, to be, but with voice mail by email, I don't miss a call.
Besides, the going Not Available sure beats being awakened in the middle of the night :-) by a call from someone who clicked on my SitoFono link!