If you are in this situation remember that for every person who does call after receiving one of your flyers, there are many that have them sitting on fridges and cupboards, etc. Also, even though most of them do get thrown away, a majority do get looked at. This certainly helps for branding purposes.
So remember: if you get a campaign or two out there there are many people are now aware of you, even if they don't call. This is important, particularly if you are starting out.
A recent example: I was doing a run in Wangara recently. I'd done the particular street I was on a couple of times before, leaving a basic flyer advertising the website promotion lessons listed here.
Anyway, doing another run in which I included this same flyer, I saw a woman standing outside a building I was approaching. She asked me how much I charged for distribution for others. I told her and said the details were on the website listed on the flyer I was distributing. Recognizing that particular one, she said she'd already received one and it was in her drawer. She thought it might come in handy later on.
So, even though she hadn't called or contacted me, it had clearly registered with her. Hopefully she'll call at some stage regarding either the distribution, or the lessons, or both! Even if she doesn't, this little experience proved that that they do make an impact, even if they appear not to.
Another example: About a year or so ago I did thousands of flyers advertising the distribution service in South Perth. Got some calls directly from them, and eventually stopped covering that area.
A few months later, someone called me regarding flyer drops. I ended up doing a run for her. When I picked up the first box I asked how she'd found me. She said Googling. Then she mentioned that a friend had received one of my flyers in South Perth and had passed it on to her. When she went to the website she saw the same number that was on the flyer. She half-jokingly said, "It was a sign". And that's when she called me. So she only acted after she'd learned of my services in two media. (I can recall other similar examples from the past, too. Actually, I think this happens a lot.)
This is why It's important to keep going with offline advertising such as flyers and local newspaper ads even if they don't seem to be working. That's because you are still raising awareness. So when people come to your site via search engines or social media, or perhaps get your number via word of mouth, they're a bit more likely to call if they've seen you in other media. Every little bit helps, as the saying goes ...