With service type ppc your just not going to get the kind of tracking that ecommerce people are. Your call to action is a phone number. One thing you can do is put your phone number in the ad. One thing we have done is to add live help to the site. Another thing you might do is only run the ads during business hours since most people are going to call or use live help. You can put questions in your ad. Try different things. Use A/B testing to see what ads do the best.