I think you wonder what is the difference between "통화하다" (not 동화하다) and "전화하다"
As you guess and Gertie commented, 통화하다 means the act of talking on the phone,
전화하다 usually means giving a call but it can be sometimes used to mean talking on the phone too.
"전화통화하다" means giving a call and talking on the phone.
"전화를 걸다" can only be used to mean "giving a call."
I think these example sentences will be helpful.
어제 남자친구한테 전화했어? Did you call your boy friend yesterday?
전화는 걸었는데, 전화를 안받아서 통화를 못했어. I did but I couldn't talk because he didn't answer the phone.
어제 형과 오랫동안 전화했어/ 통화했어. I talked to my old brother for a long time on the phone.
아버지는 지금 전화 중이세요/ 통화 중이세요. My father is on the phone now.
전화가 통화 중이에요. The line is busy.