Oh, you poor fools. You aren't going to get around them, any secretary with more than 5 minutes of training knows how to keep sales people as far away as possible so unless you're the decision maker's wife, kids, or lawyer then you're probably not going to get very far.Instead of trying to get around them, use them because they are a great sales tool. The first thing you need to do is switch the gate keepers frame of mind, if they think you're a sales person then you're nothing more than vile scum. If they think you're a customer then their only job is to be as friendly and cheerful as possible. So let's say you're pitching a restaurant, the first words out of your mouth should be "I was looking at the menus on your website". Immediately they're guard drops, because what sales person looks at food menus? And then follow it up with "and noticed a few problems with your website that the owner/manager/CEO will probably want to know about". Obviously, don't mention their actual name even if you know it because as a customer, you shouldn't. Then close it off with "if you'd like you can give them my name and number and I can explain it to them whenever they have some free time". Some will ask you what the problem is, just deflect it by saying "well it's a combination of a design flaw and a buffer overflow problem". The person answering won't know what the hell a buffer overflow is and chances are neither will the decision maker so it increases your chances of a call back by about 1,000%. Now just sit back and wait for the calls, some business owners are too smart to fall for it but phone sales is all a numbers game. When they call, make up some excuse about how you don't think their php is up to date and that they should contact their hosting company to double check, and from there work in something about a design flaw and start pitching your SEO services. Make sure you keep a spreadsheet with all the names and sites so you know who's calling and when, if you're a 1 man operation it can get tricky.
Good luck bros.