I think alot of people have a bit of problem calling (mainly it's the women's decision to employ a windy, and asks hubby to phone who's too lazy to)
so i think email address is a good idea, especially if coupled with a website ( can do your own mrsite £20)
with a website potential custy's can look at you without you knowing who they are so here is no real hard sell.
Also with the email people can contact you in their downtime at work, alot of people don't have much time when they get in from work. i.e do dinner wash up put the kids to bed, watch bit of telly bed.