Phoning...?
Difficult one this recruiting lark...
Being on the receiving end of the phone calls, it's difficult for me to say that that will be the most profitable response. When we're full, we're full so the phone calls are wasting everyone's time.
Like Flatspin says, contacts are the key - the old adage is repeated on this forum time and time again "not what you know, but who you know".
The last five or six pilots we're taken on are all know to our current pilots, that way at least we know that they get on with the people they're flying with - get out and about and pester people, but nicely! Call in on operators, actually into their offices. There's always someone hanging around who'll speak to you. Even if they're not helpful in getting you a job offer, you never know when in the future you might see some of them again.
Good luck.