Cold-Call Tips?

A little about my background: I am a junior at a semi-target school. I missed the fall recruitment and OCR. I recently have been trying to cold call local boutiques for summer internship opportunities, but it has not gone well so far. I will give some examples:

1. I called the MD (found the number on the website), and we had a short conversation. He then referred me to an associate who is in charge of the internship program. I called the associate and told him I wanted to learn more. He said he can't do interviews before their formal interview process, asked for my name, and hung up. I did not get a chance to say another word.

2. This is a common one: They often tell me they are not looking for an intern right now but will keep me in mind. I sent in my resume as requested, but never heard back again.

I am lost in the whole cold-calling thing. I know its a numbers game that I need to call more, but what should I do when they want me to stick with the online application or have no current openings right now. What could I have done in calls like this to put myself out there and make me standout of the application pool?

Also, I get discouraged from these rejections (getting hung up, etc.). I know I should suck it up and keep doing it, but how do you guys keep yourself motivated?