Somewhere along the line you're going to be faced with leaving a voicemail. You practice, practice, and practice a warm-call presentation, and then you get voicemail! Oh, brother! Well, there is a lot of debate as to whether you should leave a message on a hiring authority's voicemail. Try your own experiment and see what works. I recommend doing it. I would, however, call a hiring manager two or three times, trying to make a presentation, before I would leave a voicemail. If I come to the conclusion, after even the second time, that I'm not likely to catch this hiring authority answering the phone, I would leave a voicemail. The script for the voicemail message isn't much different from the script used when a live person answers the phone. The ending, however, is slightly different. It goes like this: _that are (advantages)__to you and your firm.
"I would like a chance to meet with you. My phone number is_.
Again, that is_(your name)_and my phone number is_."
Be sure to repeat your phone number at the end at least once, and repeat it very s-l-o-w-l-y so the person can write it down and as you record it the second time. It is just too hard for people to go back and listen to your voicemail a second time to get your phone number. If you say your name and number slowly, and repeat even more slowly at the end of the message, people are more likely to write down the information and return your call.
If you don't get response the first time that you leave a message on a voice-mail, I wouldn't hesitate to record a similar message two or three times for the same person. This sounds a bit excessive, but my experience has been that if there is even the slightest "pain" of needing someone now or in the near future, this kind of message will get the attention of a hiring authority. After all, you have nothing to lose but your anonymity.
After leaving four or five messages similar to this and not getting a response, I would stop calling, at least for now. If my experience had been with a similar kind of organization where my value might be greater than the average candidate looking for a job, I would certainly call back a number of times down the road. But, for now, I would stop calling after three or four messages.
If you do get the courtesy of that callback from a hiring authority, you would deal with it in the same manner that I have written about above. Just don't take it personally when people don't return your voicemail.
How These Things Affect You
The only way you're going to get a job offer is to interview. Getting interviews is the most important activity you can do in order to get a job. Performing well on an interview can be perfected with practice, but getting an interview is an ongoing activity.
Get them any way you can. Through your own efforts, recruiters...any way you can. I know it has dawned on you that in looking at the manner in which I suggest you get interviews there is going to be a high degree of refusal. Do not accept this refusal as a rejection. When a company does not have an opening or does not wish to interview you for any reason, you were not being personally rejected. It is simply refusal, and it means that you have to keep calling and getting appointments.
But, if the pain of not having a job or the need for a job change is greater than the pain of the refusal that you will experience, you'll get used to it very rapidly. In fact, after a while, you will be encouraged by each refusal, realizing that it is just one more refusal that is going to lead to a positive response.
Getting interviews and performing well on them are actual things you can control in the job search process. The more calls you make, the more opportunities you are going to uncover.