There might be many reasons for this.
Let me share some that I have fallen into during my life:
1) Fear of Rejection.
Fear that by calling back and making a contact, asking someone out and being rejected was OFTEN a major issue for myself in my teenage years and early 20s.
Irrational, but true.
2) Self confidence on the telephone.
Young men copy their fathers. My father rarely used the phone at home. So I grew up unconsciously copying him.
So I lacked confidence "just having a chat with a woman".
Over the last five years I have changed all of that, the phone is now my friend. Its a tool I use to touch base with people that I want to see, or find out how they are doing.
A lack of self esteem, shyness around the opposite sex was a problem for me.
In the work I do these days with other men I emphasize that making friendships with introverted or shy people is very draining. It takes a very LONG time to build trust, and get their attention.
Shy people live in their heads, feel inadequate around others, yet their silence and aloofness can give the impression they are at ease, when just the opposite is true.
So you might want to start developing a checklist about the men you are attracted to: 1) Are they shy, 2) If so are you willing to put in more effort, 3) Do they call others on the phone very much, 4) Do they have a fear of rejection.
If you keep choosing men who tick the boxes for points 1, 3 and 4 - then you are doomed to frustration and disappointment.
Hope this helps a bit.
Take care. Be well.