पर्सन-टू-पर्सन  =  telephone call
Of a telephone call- made through the operator to a particular person and paid for from the time that person answers the phonelongman- a telephone call that is made to one particular person and does not have to be paid for if they are not there

एक एक के साथ  =  between individuals
I would like to conduct person-to-person meeting to settle this dispute.

आमने सामने का  =  face-to-face
Person-to-person interaction is better than letters.