call
The Italian word 'chiamare' is used primarily to mean calling someone, either on the phone or to get their attention. It is also used to describe the action of naming or labeling something.
I had to call a plumber.
This sentence is about a simple past action. In English, this is expressed with 'had to' because it denotes a past obligation. In Italian, however, the verb 'dovuto' which is the past participle of 'dovere' is used.
I'm about to call Luca.
This phrase is about an action going to be done in the near future. In Italian, the phrase 'sto per' which literally translates to 'I am for' is used to express this. In English, it is translated as 'about to'.
Yes, I can call a taxi.
This phrase uses the verb 'posso', present tense of 'potere', meaning 'can'. This verb followed by another verb ('chiamare' in this case) expresses the ability to perform an action. In English, this construct is represented by 'can'.