Historically men often pursued women with calls, letters, poems, flowers, and showing up to carry heavy items and so forth. I know one elderly woman who told me she turned down her deceased husband for a date at least 10 times before she finally agreed to go out.
Today that man would be considered a "stalker"!
In the modern era most people don't want to "play games". Not many men are going to risk being labeled a "stalker" or accused of "sexual harassment" for flirting with a woman who shows no sign of interest.
"Meet me half way" is the mantra of today! If a man doesn't detect there is a (mutual interest) then he will move on. Most women are aware that (other women are not) playing "cat & mouse" games.
As for ignoring the phone calls apparently a lot of women are afraid of "losing themselves" in relationships. They worry about not appearing to have (a life) of their own. Therefore they don't want their men to believe they're always "available". It's better to have a life than to fake a life. Wherever you go there you are.
Even if he "thinks" you're busy (you) will know you weren't. Suppose he asks you what you were doing or where you were....then what?
Lying is never the best way to build a relationship in my opinion.